Mosquitoes. Hordes of them, buzzing in your ears and biting incessantly, a maddening nuisance without equal. And not to mention the devastating health impacts caused by malaria, Zika virus and other pathogens they spread.

But mosquitoes have a whole other life that doesn’t involve biting us; it revolves around their ecological interactions with plants.

We often view mosquitoes as bloodsuckers that do nothing but make our lives miserable. However, mosquitoes do have ecological functions. From pollination to ant puke, the secret life of mosquitoes is both bizarre and ecologically important.

Mosquitoes have many functions in the ecosystem that are overlooked. Indiscriminate mass elimination of mosquitoes would impact everything from pollination to biomass transfer to food webs.

Mosquitoes that pollinate

There are about 3,500 mosquito species, many of which want nothing to do with biting humans or any other animal. Even in species that bite, it is only the females that do so and just to develop their eggs.

The fundamental food of all adult mosquitoes is plant sugar and its associated nutrients, most often in the form of floral nectar. In the process of looking for nectar, mosquitoes pollinate many of the flowers they visit — this is one of the most commonly overlooked ecological functions of mosquitoes.

Mosquito pollination is likely far more common than we realize. There is evidence that mosquitoes function as generalist pollinators in some plant families, and there are many known instances of mosquito pollination that are simply overlooked.

Mosquito pollination was observed as far back as the 19th century. Mosquito pollination is hard to see, as most mosquitoes visit flowers near or after dusk and human presence disturbs mosquitoes from nearby flowers. In the Arctic, plants make use of vast hordes of nectar-hungry mosquitoes for pollination during the short growing season.

Mosquito evolution

The connection between mosquitoes and flowers is ancient and has likely had a strong influence on mosquito evolution. Genetic evidence supports a rapid increase in mosquito diversity corresponding with the appearance of flowering plants. Mosquito scales have been found in flower fossils from the mid-Cretaceous era.

Mosquitoes locate flowers by a variety of cues including odour and vision, and recent research has discovered that some of the odour constituents of certain flowers that mosquitoes feed on (and pollinate) are shared with humans. One interpretation of this is that to mosquitoes, some flowers may smell like humans, possibly indicating the evolutionary origins of why some mosquitoes take blood.

Sourcing honeydew

While less ecologically important than pollination, mosquitoes also consume plant sugar that has been processed by other insects.

Plant-sucking insects such as aphids excrete a sugary waste product known as honeydew, which is exploited as a food source by many insects, including mosquitoes. But honeydew is hard to find in the environment. Mosquitoes have solved this problem by using the smells emitted by microbes that live in the honeydew to locate it.

Additionally, honeydew is famously consumed by many ants, which farm aphids to collect honeydew. An ant can, through strokes of its antennae, induce a compatriot that has recently eaten honeydew to regurgitate and share some of its meal. Some mosquito species have learned to exploit this for their own benefit.

When a mosquito inserts its mouthparts into an ant’s mouth and strokes the ant’s head with its antennae, it tricks the ant into regurgitating and sharing its honeydew.

Biomass transfers

Mosquito larvae grow by consuming microorganisms such as algae and microbes that decompose decaying plant material. Larval mosquitoes contribute to aquatic food chains by serving as food sources for many predators, including fish and birds.

If a mosquito survives to adulthood, it flies away from its aquatic habitat. This transfers the mosquito’s biomass (its material weight) to the terrestrial ecosystem.

Adult mosquitoes are eaten by many creatures including birds, bats, frogs and other insects. Adult mosquitoes that die (or are eaten and excreted) then decompose, turning the microbes they consumed as larvae into nutrients for plants, completing another important ecological function.

Mosquito biomass has been calculated at 96 million pounds in Alaska alone. While the contribution of nutrient-cycling by mosquitoes to plant growth and other ecosystem functions remains unstudied, the amount of biomass involved implies that it may be important.

Unique homes

Mosquito larvae can be found in most types of freshwater, from temporary snow-melt pools to lakes. They can even be found in a few types of saltwater habitats such as crab burrows.

One of the more interesting habitats that mosquito larvae can be found in are the pitchers the carnivorous plant Sarracenia purpurea. These pitchers are filled with water and decomposing insects that provide food to both the plant and the mosquito.

The digestive enzymes in this plant are too weak to dissolve the mosquito larvae. Several mosquito species place their eggs in the water that collects between the leaves of tropical plants in the Brazilian Atlantic forest, and the larvae of some other mosquitoes attach themselves to the roots of aquatic plants to breathe.

Disease reduction, ecosystem balance

Mosquitoes are also the world’s deadliest animal and cause immense suffering. Ideally, we should maintain the ecosystem functions of mosquitoes while also reducing disease burden.

Not all mosquito species are responsible for spreading pathogens. Targeting specific species or making the mosquitoes themselves immune to pathogens and thus unable to spread them would protect humans while keeping the ecosystem function of mosquitoes intact.

In a world of collapsing ecosystems and declining pollinator populations we need all of the help we can get. This includes acknowledging the secret lives of mosquitoes and more sophisticated mosquito control strategies that protects their ecosystem functions.

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Daniel A.H. Peach, Postdoctoral Fellow, Department of Zoology, University of British Columbia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Top header image: John Tann, Flickr

Powerful jaws feature so prominently in science articles and documentaries that descriptors such as “bone-crunching” or “lightning-fast” hardly mean anything anymore. We’re all familiar by now with the animal kingdom’s impressive array of armaments, and jaws are some of the most widely-used tools for catching prey and defending oneself. Among the diverse cast of characters with menacing mouthparts, trap-jaw ants (Odontomachus sp.), although tiny, are awe-inspiring in their own right. With jaws that open a full 180 degrees and span a distance significantly wider than their heads, the ants can strike at the breathtaking speed of 225 kilometres (140 miles) per hour and with a force 300 times the insects’ own weight. In addition to the more conventional functions that jaws perform in other animals, trap-jaw ants employ theirs in a truly novel way: locomotion.

Whenever a quick escape is required, the insects press their heads into the ground, slam their jaws shut, and fling themselves a distance that’s equivalent to an average-sized person jumping 40 metres (130 feet) through the air. As biologist Sheila Patek describes it, “In regular, daily time, the ant is on the ground – and then you can’t find it.” Patek’s lab at Duke University specialises in studying some of the fastest motions in the animal kingdom, and trap-jaw ants are at the centre of a ground-breaking partnership she forged with engineer Zeynep Temel from the Wood Microrobotics Lab at Harvard University. Temel, who uses origami-inspired metal folding techniques to create tiny robotic structures, is drawing on Patek’s deep knowledge of trap-jaw ant biology to develop new obstacle-jumping microrobots. Meanwhile, Patek has learned something from their partnership that she never expected – and it’s fundamentally changed biologists’ understanding of how the ants achieve their jaw-dropping acrobatics.

Header image: Katja Schulz

Word of the spotty zebra – given the name "Tira" by the guide who first found him – quickly got around and photographers and tourists in the area rushed to catch a glimpse of the unusual animal. “At first glance he looked like a different species altogether," photographer Frank Liu told National Geographic. While Tira may look like he's been crossed with an okapi, he actually owes his unique colouration to a rare genetic condition called pseudomelanism.

Skin and hair colour in mammals comes from a pigment protein called melanin which is produced by specialised cells called melanocytes. In humans, melanin acts as a natural sunscreen, darkening the skin to help protect it from harmful UV rays."There are a variety of mutations that can disturb the process of melanin synthesis, and in all of those disorders, the melanocytes are believed to be normally distributed, but the melanin they make is abnormal,” Greg Barsh, a geneticist at the HudsonAlpha Institute for Biotechnology, explained to National Geographic.

Under their striped coats, zebras have uniformly black skin as a result of melanocytes being evenly distributed across their bodies. According to Barsh, pseudomelanistic zebras like Tira have all of their melanocytes in place, but the melanin produced does not result in stripes, for unexplained reasons.

Zebras with unusual colour patterns are rare, but not unheard of. In 2014, a black zebra was photographed in Botswana's Okavango Delta, while a 'blonde' individual showed up in the Serengeti earlier this year. Unusual colouration is likely to put the animals at greater risk of falling victim to predators, according to University of California biologist Dr Tim Caro. "Some predators choose members of herds that stand out because it may signal that they are not so good at fleeing," he explained to us via email.

This does not necessarily mean that stripes are effective at deterring predators, he adds. In fact, Caro's research indicates that zebra stripes could have evolved to aid in repelling disease-carrying flies. Field experiments show that horse flies are less likely to land on striped surfaces, which puts darker animals like Tira at increased risk of contracting trypanosomiasis, African horse sickness and equine influenza, all of which are spread by biting flies.

Although Tira's sensational polka dots make him stand out in the herd, it's unlikely that his strange colouring will result in rejection from other zebras. Field studies in South Africa found two cases of zebras with atypical colouring that were able to form normal relationships with other herd members. Provided Tira can make it to adulthood, he should be able to fit right in.

Black mambas are extremely dangerous reptiles – in fact, many consider the species to be one of the world’s deadliest snakes. They are found in southern and eastern Africa, and are shy, evasive creatures. They won’t seek out human interaction. But if cornered or confronted, they will strike. And their venom is lethal.

Black mambas (don’t let the name fool you – they’re very rarely black, and are more usually a dark brown – it is the inside of the mouth which is black) probably cause the largest number of snake-related deaths in southern Africa. In a recent case, a South African judge died after being bitten by a black mamba while he was travelling in Zambia. But the data for the whole continent is limited, so the precise number isn’t known. This is chiefly because most of these deaths occur in rural parts of Africa with limited health infrastructure and other resources.

Sub-optimal mortuary facilities, inadequate professional manpower, poorly developed protocols and the lack of an efficient and reliable toxicology service means many of these deaths in Africa’s more rural areas are not properly diagnosed. It is most likely that these snakebite victims get buried without a thorough forensic pathological autopsy.

The black mamba is born with two to three drops of venom per fang. It is a front-fanged snake, with fangs up to 6.5 mm in length, located at the front of the upper jaw. An adult of the species has between 12 and 20 drops per fang. It takes just two drops of venom to kill an adult human. This means that even young black mambas are extremely dangerous.

Not much is known about the pathology of trauma of black mamba bites – that is, what the black mamba’s toxin does, physically, inside a victim’s system. We do know that the venom is neurotoxic and cardiotoxic. That means that it has a direct effect on the nerves and the heart.

The more we know, the better. If we know precisely what the toxin does, hospitals and clinics might be better prepared to treat those who’ve been bitten.

A recent case study

Recently my colleagues and I examined the case of a young man who was bitten by a black mamba in South Africa. He arrived at the hospital 20 minutes after being bitten and had already suffered cardiac arrest with accompanying hypoxic brain injury.

This was my third encounter with the victim of a black mamba bite. My first encounter, in 2000, involved a 12-year-old girl who was fatally bitten on the thigh by a black mamba. The second involved a British tourist who was accidentally bitten at a snake park, and who also died.

In this latest case, the co-workers of the young man who died were certain that the snake was a black mamba. This gave us, as forensic pathologists, an excellent opportunity to thoroughly investigate this matter. Oftentimes, the history is scant, with victims unable to properly identify the snake which bit them.

The forensic examination consists of a thorough macroscopic post mortem examination, followed by histological (microscopic) examination and blood tests.

A black mamba’s venom is complex. It interferes with transmission across the motor end-plate, which is where the nerves and muscles connect, so it will result in paralysis. The venom is also cardiotoxic, which means it may have a direct effect on the heart.

How to treat it

So what should you do if you or someone around you is bitten by a black mamba?

The first priority is to transport the victim to an appropriate medical facility as soon as possible. First-aid should focus on maintaining vital functions, such as respiratory support. Keep the victim still and try limit any unnecessary movement. Remove constricting items (for example rings and clothing), especially those close to the bite site.

The first-aid treatment of black mamba bites includes lymphatic retardation with the pressure immobilisation technique – in other words try and wrap a tight crepe bandage or tourniquet close to the bite site.

Medical management comprises continuous monitoring, making sure the airways are open, treating symptoms and the immediate administration of antivenom. The antivenom is injected intravenously because absorption is poor via the muscles. It’s also important not to inject into or around the bite site. In rare instances the victim may be put on extracorporeal membrane oxygenation, which is a way of providing prolonged cardiac and respiratory support to those whose heart and lungs are unable to provide oxygen to the body.

This combination of respiratory support and antivenom may save a person’s life. Over time, the antivenom will ease muscle paralysis and set the victim on the road to recovery.

Ryan Blumenthal, Senior Specialist, University of Pretoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Every summer evening, deep in the Hill Country of central Texas, hundreds of thousands of Brazilian free-tailed bats (Tadarida brasiliensis) pour from the mouth of a limestone cave. The pungent smell of guano and the rush of sound and air from so many wings beating at once is an experience that truly overwhelms the senses. Then, just like that, it’s over—in a matter of minutes, members of the entire colony have emerged from the cave and disappeared into the dusk for their nightly foraging flight.

To the naked eye, in real-time, the colony exodus is a blur of wings and bodies moving too fast to track. Yet somehow, the entire colony manages to exit the cave, night after night, without traffic jams or (many) casualties. How do they achieve this incredible feat? Scientists Nickolay Hristov and Louise Allen set out to answer this question. Using high-speed video cameras, they have captured these events — and interactions among individual bats — in spectacular detail. Now, frame by frame, they are discovering that it’s not always necessary for nature to come up with the perfect solution — just one that’s good enough.

It’s no secret that chameleons possess remarkable tongues. Aristotle first described the breathtaking speed of chameleon tongue projection around 300 B.C. But the tongue lashings these lizards deliver to unsuspecting prey happen in such a blur that scientists have historically understood very little about the mechanisms that make them possible.

Now, with the help of new imaging technology, University of South Dakota scientist Christopher Anderson is unfurling the mysteries behind one of the most amazing fast-food feats on the planet. Armed with a high-speed camera – and a homemade “cricket trapeze” – Anderson has recorded tongue strikes from chameleons large and small.

One species, a chameleon tiny enough to fit on your thumb, projects its tongue at a rate of 2,590 meters per second squared (8,497 feet per second squared). That’s equivalent to a car going from 0 to 60 (miles per hour) in one hundredth of a second. No reptile, bird, or mammal has ever been documented achieving such astounding acceleration. What’s the secret to the chameleon’s special skill? Anderson’s 3,000-frame-per-second videos are revealing some surprising answers.

Header Image: bioGraphic

How is it possible that an animal, any animal, can survive the dead of an Antarctic winter? No food, no shelter; just ice, cold, and wind for more than a hundred days straight. But that’s exactly what emperor penguins (Aptenodytes forsteri) do – not only surviving, but breeding in one of Earth’s most inhospitable environments.

To the casual observer, the birds appear to just stand around on the ice and endure their frigid world. A longer look, though, reveals that penguins often form tight groups, especially when temperatures plummet. This “penguin huddle” appears to be at the core of the birds’ ability to conserve body heat and survive outside temperatures that would kill most other creatures. But exactly how these huddles function and how they subtly change in shape over time to benefit all members of the group has remained a mystery.

To explore the secrets of the penguin huddle, physicist Daniel Zitterbart and his team at the Woods Hole Oceanographic Institution set up an elaborate network of robotic time-lapse cameras at a remote Antarctic research station in Atka Bay. Although the researchers control their cameras from half a world away, they have been able to capture an intimate portrait of life inside the penguin colony. High-resolution time-lapse imagery and computer analyses enable them to see and measure movements of individuals in the group that would otherwise go unnoticed. These movements, while subtle, are highly coordinated and critical to the survival of both individuals and the colony as a whole. And importantly, Zitterbart’s team now thinks their observations can provide important information about the overall health of emperor penguin colonies – and allow scientists to better predict how this endangered species will respond to changes in temperature, sea ice, and other environmental factors related to climate change.

Fire and critters have also lately been in the news courtesy of a fascinating study published late last year in The Journal of Ethnobiology investigating the so-called "firehawks" of Australia's tropical savannahs. Its authors delved into a phenomenon long known to Aboriginal peoples: raptors plucking flaming or smouldering sticks from bushfires and dropping them in nearby grass, thus sparking a new burn.

To some people who've never experienced one where they live, or where they love to recreate, a big burn can seem a disastrous aberration – and, ala Bambi, nothing but trouble for the creatures caught in its path. The intriguing case of the firehawks (which we'll explore a bit more later) suggests a more complicated story. Most of the world's ecosystems have evolved with fire of one kind or another, and animals have an instinctive (and opportunistic) relationship with it.

Let's have a look at some of what we know about a fire's impact on animals: the bad, the good and the grey areas in between.

Fire in ecosystems: An old story

First though, setting the stage. A remarkable share of ecological landscapes evolved under the regular influence of flame, though what sort of fire, and how frequent, and from what ignition source, vary considerably. Many Mediterranean-zone and semiarid grasslands, shrublands and woodlands burn chronically: from the fynbos of South Africa's Cape region and the eucalypt woods of southeastern Australia to the cerrado savannahs of central Brazil and the California chaparral. But many other plant communities that wouldn't seem terribly flammable at first glance – cold subalpine woods, northern taiga, temperate rainforest – do indeed burn, even if the intervals between fires are sometimes on the order of several centuries, even a millennium.

Lightning conspires with annual dry seasons or periodic droughts to spark wildfires, but we – human beings – are just as important ignition sources in many parts of the world. We've been intentionally starting fires for thousands of years: to improve hunting or herding opportunities, to clear land for agriculture and manage crops. The exact fire regime of a region depends on a whole suite of factors, but generally speaking a place that burns frequently tends to experience low-intensity fires – there's not time in between burns to build up a lot of fuel, basically – while countryside that tends to ignite once every few centuries will nourish bigger, fiercer fires.

An inferno raging through a forest or brushland may look apocalyptic, and some individual animals will perish in it, but such a blaze can also help maintain and rejuvenate the resources local wildlife depends on – and open up crucial opportunities for other species specially disposed to capitalise on the post-fire landscape.

But what about those real-time effects of the leaping flame and billowing smoke? What about the critters that perish, and those that don't?

Mammals

It's often surprising how few medium-sized and large animals appear to die in wildfires. In the mighty conflagrations that roared across Yellowstone National Park in 1988 (and changed wildfire philosophy and policy in the USA), known large-mammal deaths were in the low hundreds: 240 elk, nine bison, four mule deer, a pair of moose – most of them apparently felled by smoke inhalation. Reports of Yellowstone's big beasts running from the big crown fires were scarce; the main reaction was basically indifference. Several radio-collared grizzly bears hung around actively burning areas during the '88 Yellowstone fires, and more than a dozen grizzlies moved right into burned-over zones after the flames subsided. "Bison, elk, and other ungulates grazed and rested within sight of flames, often 100 metres or less from burning trees," noted a United States Forest Service report on the ecosystem impacts of wildland fires.

One basic reason why bigger mammals often escape a fiery death? Well, because they're pretty good at galloping, loping, trotting, even plain sauntering away from flames. The hair of mammals also provides a bit of a buffer against the extreme heat, especially longer and denser fur. This means they can sometimes get away with slipping right across a fire front. (That sort of doubling-back, for example, allowed several woylies – little kangaroo cousins – to remain in their home ranges during a moderate-to-high-intensity burn in a eucalypt forest in southwestern Australia.)

This past December, the manager of the free-roaming American-bison herd in South Dakota's Custer State Park noticed the bovids' shaggy coats seemed to offer some protection during a fierce and fast-moving grassfire: outer guard hairs were burned off, but the "underfleece" beneath provided a shielding layer.

That prairie blaze – which blew up from 4,000 to 35,000 acres on a single night due to winds exceeding 40mph – caused burns severe enough that a number of bison (as well as elk, deer and a feral burro) had to be put down. It goes to show that a swift wildfire can sometimes outpace or outflank even the large and the mobile: whether it's mustangs in the American West or elephants in South Africa, big mammals do sometimes fall victim to flame and smoke.

"Large mammal mortality is most likely when fire fronts are wide and fast-moving, fires are actively crowning, and thick ground smoke occurs," the US Forest Service report explained.

After the Jasper Fire of 2000 – the largest to impact the Black Hills of South Dakota and Wyoming in modern times – researchers studying pumas in the range found one of their radio-collared cats, an adult female, dead in a mountain draw. They concluded that the puma, which had burned paws and singed whiskers but otherwise minimal external injuries, had asphyxiated, probably on a day when strong south winds had driven the fire front forward at some 15mph – fast enough, they reasoned, to trap the animal in the draw.

Smaller mammals such as rabbits and rodents may also run away ahead of the flame front, or retreat underground. Ventilation is vital, though: mice have been found suffocated post-fire in burrows with only a single entrance.

Some mammals are more vulnerable to fires than others. Koalas, for example, a bit ungainly on the ground and prone to shelter in the canopy, can get in trouble when a bushfire rages through their highly flammable (and fire-dependent) eucalypt woods. Fire can also hit woodrats hard, as those rodents hole up in aboveground nests of grass and other litter – super-combustible homes they're loathe to abandon even when flames start crackling.

Reptiles & amphibians

Like small mammals, reptiles and amphibians may either flee fires or successfully endure them ensconced underground or within crevices, rotten logs and other cool, moist hidey-holes. In 2001, wildfires in New Mexico burned the entire known range of the endangered Jemez Mountain salamander, yet the population survived due to the refuge offered by rock nooks and crannies. Timing's everything, though: snakes in the process of shedding their skin may be less adept at sheltering from a fire.

Birds

Adult birds are pretty well set up to simply fly away from conflagrations, though eggs and chicks are vulnerable: surface or understory fires may destroy nests laid on the ground or in shrubs, while canopy broods go unaffected. (How significant the loss of a nest to fire is can depend on the species: as the US Forest Service notes in its wildfire/ecosystem survey, wild turkeys often don't re-nest if their brood is lost after a few weeks of incubation, whereas another upland game bird, the northern bobwhite, may re-nest several times a season.) In many fire regimes, however, peak burning season occurs after peak nesting.

Flying birds, well equipped as they are to dodge flames, may – like those big mobile mammals – sometimes be overwhelmed. A 1999 fire in the South Florida Everglades didn't harm two large rookeries of wading birds – even as sawgrass marsh around them burned, the "tree islands" harbouring the rookeries were wet or moated enough to endure – but it did kill 50 white ibises that were likely trapped by heavy smoke while out foraging.

Now, what about those pyromaniacal Aussie raptors? Birds of prey in many parts of the world commonly hunt along and above the fire front, scavenging crispy leftovers and feasting on the small creatures driven ahead of the flames, as well as insects lofted high by the fire thermals. But recent research has investigated the possibility that certain Australian raptors intentionally spread flames to flush out (and fry) more snacks. A National Geographic article on the study quoted a passage from the 1964 life story of an indigenous man named Waipuldanya Phillip Roberts that helped inspire the investigation: "I have seen a hawk pick up a smouldering stick in its claws and drop it in a fresh patch of dry grass half a mile away, then wait with its mates for the mad exodus of scorched and frightened rodents and reptiles. When that area was burnt out, the process was repeated elsewhere."

The researchers delved into traditional knowledge and mythology on the subject and also documented contemporary observations bearing out the firehawk behaviour among three quintessential raptors of Australia's northern savannahs: the black kite, whistling kite and brown falcon. Not everyone's convinced the birds' spreading of fire is intentional – it's also been proposed they accidentally nab smoking sticks in their talons when making unsuccessful predatory strikes – but the research team is continuing its inquiry, and hopes to record the firehawks in action on film.

Invertebrates

It's difficult to summarise what we know about wildfire impacts on invertebrates. Many aboveground insects and arachnids likely perish during fires, although one study* showed both adult acridid grasshoppers and nymphs were quite capable of escaping a savannah fire in Côte d'Ivoire. In many cases, invertebrate numbers and diversity recover quickly in burned zones due to dispersal from neighbouring unburnt habitat (though a recent study on Florida tortoise beetles showed recolonisation can take a good while for some bugs).

Invertebrates that tunnel into the litter layer or soil probably hold up better in fires, though high-severity burns have been known to destroy even subsurface eggs of mites. (In that case, incidentally, mite populations in the burn area were initially lower than surrounding plots, but by a year and a half post-fire, the burn area supported substantially higher populations than elsewhere, a trend often seen for aboveground invertebrates as well.)

Certain kinds of insects, meanwhile, are actively attracted to fires. Charcoal beetles (Melanophila) sense the heat of wildfires as far as 130 kilometres away and "beeline" for them (if you will) to mate and lay eggs beneath the bark of fire-killed snags. Writing in Bay Nature about the 2013 Morgan Fire near San Francisco, Emily Moskal described firefighters' vivid experiences with hordes of these beetles:

To protect themselves against the darting insects, the firefighters wore bee veils. The beetles emerged from their mating stages in the burned or burning trees to swarm, rising with the smoke and sizzling crackle of extinguished embers. Firefighters recalled that everywhere skin was exposed, beetles scratched and prodded ... [Firefighter Dylan] Jorgensen described a feeling of relentless buzzing in his hair, firefighters "ripping their helmets off like feeling a bee in your shirt," and dancing and shaking to get the beetles off of them.

Other types of wood-boring beetles as well as horntails (or wood wasps) follow the scent of smoke to reproduce in burned forests. "Firebug" is a common shorthand for all of the insects for which wildfires are one big smoking magnet.

Indirectly dangerous 

Animals aren't just killed outright by voracious flames and choking smoke. There are also dangers only indirectly related to fire – which would include, for example, the predation inflicted upon those skittering mice and snakes and insects fleeing the fire front.

Creatures retreating from fire face other risks, too. In one instance, a slew of Cape grass lizards were squashed on a gravel road they were crossing to escape a fynbos blaze.

What's more, injury from flames may hamper an animal's ability to obtain food or avoid predators. In early October of last year, a closely monitored male puma in Southern California's Verdugo Mountains turned up dead not long after a 7,000-plus-acre wildfire in the area. While the cause of his death was unclear – a necropsy ultimately ended up finding traces of rat poison in his system – a National Park Service spokesperson told LAist, "We've seen other cases of mountain lions surviving wildfires, and coming away with burned paws that make it difficult for them to hunt and survive."

Fire & wildlife habitat

The real-time deaths and miraculous escapes are the most superficially dramatic wildfire impacts on wildlife, but more significant in the long-term are the habitat changes resulting from burns. As firebugs demonstrate, these changes create opportunities for many animals.

"Fire turns the kaleidoscope of habitat. The post-burn environment favours some species, discourages others, which is why you want lots of patch burns so you have a good churn of habitat," Stephen Pyne, one of the foremost wildfire scholars around (and a former wildland firefighter) told me via email.

Amid the bountiful sunlight and released nutrients of a charred forest or shrubland, grazing animals may prosper; browsers may get their day when early-successional shrubs colonise burns and reign for a few decades. Woodpeckers and other cavity-nesting birds flock to the snags that stud a burned forest. The "case-hardening" by which flames toughen wood means that a fire-killed snag and the downed log it ultimately produces – apartment complex for all kinds of creepy-crawlies – may offer longer-lasting habitat than other deadwood.

Fire's impact on habitat varies from fire regime to fire regime, of course. A grass fire creeping across savannah or prairie preserves that ecosystem by killing invading trees and shrubs: many animals of the pre-fire landscape therefore reoccupy it in short order, if not immediately. A huge stand-replacement crown fire in taiga or subalpine forest, by contrast, removes its defining conifers and paves the way for fundamentally different plant communities – brushfields, deciduous woods – that will eventually, maybe a century later, transition back to conifer domination. More specialised animals found in the pre-fire old growth may not reoccupy the site until that happens, but in the meantime, a host of other species will stake their claim.

In the fire-dependent Cape fynbos of South Africa, nectar-eating sugarbirds and orange-breasted sunbirds lose local habitat to fire – it may take some eight years for their preferred nectar-bearing shrubs to reestablish themselves – while insectivorous species such as the Cape rockjumper may prosper on the heels of flame. In the grasslands of southeastern Arizona, cotton rats declined after a fire temporarily reduced the green vegetation they eat, while cotton mice and kangaroo rats increased in the area, likely because of plentiful seeds (their preferred nosh) generated by the forbs colonising the burn-scape.

Roughly speaking, animals specially adapted to fire environments ("pyrophytes"), as well as generalist species, tend to be the short-term "winners" when the smoke clears, while those reliant on habitats or resources that are temporarily destroyed are the "losers". Woodland caribou lose out on winter lichen reserves for a time when their boreal woods burn; white-tailed deer and moose, meanwhile, do well on account of all the abundant post-fire shrubbery.

Beyond the short-term aftermath of burns, it's important to emphasise just how many animals depend on habitats maintained directly by fire. The Kirtland's warbler is a classic North American example. The songbird – restricted to a small breeding range in Ontario, Michigan and Wisconsin, and wintering ground in the Bahamas – nests only in young stands of jack pine: a "serotinuous" tree bearing a large proportion of cones that open only when unsealed by fire. Historically, wildfires perpetuated both jack pine in general and the youthful, scrubby pinewoods the warblers needed; fire suppression has reduced warbler habitat, and prescribed burns (and selective timber harvest) are helping to restore it.

The evolving fire-scape

Part of the crazy complexity of fire ecology is the human element. We're fire animals like none other: our mastery of fire, right up there in our top two or three all-time breakthroughs, didn't just transform our ways of life – it also transformed ecosystems all around the world. Fire is an age-old force on Earth, one we learned to make and manage; for millennia, other organisms have evolved under the rhythms of anthropogenic burning.

Those rhythms, though, have changed considerably across time, as hunter-gatherer burning gave way in many areas to agricultural burning, and, in modern times, as intentional burning gave way to fire suppression. Again, it's complicated, but generally, policies of suppressing fires have built up fuel loads in many flame-adapted ecosystems to the point where they're prone to high-intensity, high-severity burns – as opposed to the low-grade fires that, erupting frequently, once maintained them.

In landscapes subject to institutional fire suppression and not, there's the even greater influence of climate change, which from the American Southwest to the Russian taiga seems to be promoting larger, fiercer and more frequent conflagrations. Climate change is such a planetary-scale, whole-earth-system phenomenon that it's an epic challenge to predict how specifically it'll influence local fire regimes, though more and longer-lasting droughts, higher annual temperatures, receding permafrost, and diminished and faster-melting snowpacks certainly seem to set the stage for more burning. Assessing how wildlife can adapt to an evolving new pattern of wildfire is just one part of the high-stakes puzzle climate change presents.

Our burning behaviour and effects on global climate coincide, of course, with all the other ways we impact wildlife. California condors, for example, have dealt with wildfire in western North America for many millennia; countless nests must have gone up in flames. That's less of an issue when you've got lots of condors, but today, the potential loss of just one nestling – like the chick caught in the Thomas Fire – is a major cause for concern.

"If you have a species tied to a particular place, isolated in a refugia, it may suffer from a big burn that blasts over the site," Pyne said. "Apart from any immediate fatalities, the species won't have any place else to flee to until the original site recovers."

Hemming wildlife into small, isolated patches of habitat surrounded by human development or otherwise unfavourable landscapes makes animal populations more vulnerable to fires, as they may have less ability to seek refuge and food, and fewer source populations for recolonisation. In this way, fires may have contributed to the extinction of the heath hen of eastern North America (a bird dependent on fire to maintain its favoured open habitats) when they broke out in the last remaining stronghold of its hugely reduced range, the New England island of Martha's Vineyard.

Meanwhile, a nearly 50,000-acre wildfire last year in the Pinaleño Mountains of southeastern Arizona killed 217 of 252 known Mount Graham red squirrels, and destroyed many of the rodents' seed caches. Scientists are anxiously hoping enough squirrels survive this winter to give the endangered subspecies a fighting chance in the wild.

If your main takeaway from all of this is that it's tough to generalise about fire impacts on animals – well, you've got it. Flames burn up woodrat nests and yet refresh wildebeest pasture. They destroy the boreal owl's old-growth home while making a new snag-ridden one for some of its close kin. They serve up a smorgasbord for hunting kites and a nursery for charcoal beetles. They pay off for this puma with lots of wild room to roam while mortally threatening that puma living in a pocket refuge walled in by humanity. Wildfire is such a defining element of so many ecosystems around the world that it's impossible to imagine them – and their constituent creatures – without it.

(Hey, did you know there's a connection between California condors, fire and Johnny Cash? No? Check out Stephen Pyne's blogpost for the story, which dates from the country legend's wild years...)

* Gillon, Y., 1972. The effect of bushfire on the principal Acridid species of an Ivory Coast savanna. Proceedings of the Tall Timbers Fire Ecology Conference 11, 419-471.

We all know that individuals fight over potential love interests. Just think of Daniel Cleaver (Hugh Grant) and Mark Darcy (Colin Firth) scuffling – rather impotently – over Bridget Jones in a fountain. But you might be surprised to hear that the fierce rivalry continues behind the scenes – in the form of sperm competition. This is when the sperm of two or more males compete inside the reproductive tract of a female to fertilise the eggs, something that is widespread in the animal kingdom.

It is generally assumed that the sperm in a female's reproductive tract around the time of fertilisation will belong to one male. But DNA fingerprinting has revealed that even "monogamous" bird species that form exclusive pair bonds are not as exclusive as was once thought.

In fact, extra-pair young (those fathered by another male) are found in around 90% of bird species, and extra-pair copulations (matings with a different male) result typically in 11% of all young. (The percentage of extra-pair young can be as high as 76% in species such as the superb fairy wren.)

Fertilising an egg is often likened to winning a lottery – the more tickets you possess, the higher your chances of winning. Consequently, the more sperm a male manages to get to the egg, the greater his chances of fathering offspring. This has led to huge variation in copulatory behaviour and sperm morphology.

Here are five elaborate methods that have evolved to increase the chance that an individual male's sperm is the winner:

1. When big is best

The obvious way to increase the chance of fertilising an egg is to increase the number of sperm that are produced. Males have been found to make the most sperm in species where individuals are most promiscuous. For example, the testes of gorillas – a monogamous species – are 30 grams, whereas the testes of chimpanzees – a promiscuous species with multiple mates – are a whopping 120 grams. To put this in context, human testes are around 50 grams, and chimps are around two thirds our body size, making chimp testes, relatively speaking, almost four times the size of human ones.

2. Sperm 'trains'

In general, larger sperm (specifically, those that are longer) are more successful because they have a greater swimming velocity. So, sperm length is longer in more promiscuous species. One animal that has truly taken advantage of this is the wood mouse, where the sperm possess hooks to attach to each other.

This means they can form aggregations, or mobile "trains", of hundreds or thousands of sperm cells, greatly increasing sperm motility.

3. Kamikaze sperm

Around 20% of sperm are abnormal – possessing two heads, no heads or two tails, for example. These “kamikaze” sperm are incapable of fertilising eggs but it is thought that they might be able to prevent sperm from rival males reaching the egg, either by killing them with enzymes or simply by blocking them. Although there is little evidence of kamikaze sperm in non-humans, some snails possess abnormal sperm that contain enzymes capable of degrading sperm.

4. Preventative behaviour

Many males cement up the genital opening of the female with a copulatory plug, producing an obstacle to prevent other males from further copulations. For example, male European dwarf spiders produce a plug which starts as a liquid secreted by a specialised gland and then hardens to become an obstacle. What’s more, the longer the copulation, the larger the plug left behind. Smaller, fresher plugs are relatively easy for other males to remove. But males are unlikely to try to remove larger plugs, benefiting those that have invested more time in the female.

5. Brushes and whips

If females mate with multiple males, each suitor generally will father more offspring than the previous one. Therefore, males compete by trying to ensure their sperm is the one to fertilise the egg.

This has led to the evolution of some bizarre penises. The echidna (a spiny, egg-laying mammal), for example, has a four-headed penis – although only two heads ejaculate at once.

In some species, penises are specifically shaped to pack sperm tightly into the corners of the female reproductive tract, whereas others are armed with spines, brushes, barbs or hooks to scrape out the sperm of previous males, or stimulate the females to release sperm. The most elaborate are the penises of odonata, insects such as dragonflies. Some even possess whip-like flagella to remove rival sperm.

These removal methods are quite successful as even the human penis is able to remove 90% of sperm from a reproductive tract.

Many reptiles, rays and sharks actually possess two "penises". In sharks, these are known as claspers, and either one can be used to inseminate the female. These claspers not only possess small hooks to anchor them in place, but they are also linked to siphon sacs filled with seawater that spray the sperm into the female reproductive tract under pressure. It has even been theorised that one of the claspers could act as a "jet wash", cleaning out the sperm of previous males, although there is little evidence for this as shark matings are rarely observed.

Whatever the reason, it is clear that animals have evolved some extraordinary ways of ensuring that they win the competition for fertilisation.

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Top header image: Pixabay

Louise Gentle, Senior Lecturer in Behavioural Ecology, Nottingham Trent University

This article was originally published on The Conversation. Read the original article.

In Disney's film version of "Pinocchio, the boy-puppet rescues his creator Geppetto by lighting a fire inside Monstro the whale, who has swallowed them both. The fire causes the whale to sneeze, freeing Pinocchio and Geppetto from their gastric prison.

Before you dismiss this getaway as incredible fantasy, consider that new research shows that a kind of fire in the belly can actually be an effective strategy for escaping predators in the real world. In fact, the animal kingdom is full of amazing examples of unusual defence mechanisms that help small creatures avoid a nasty fate.

In a new paper in Biology Letters, scientists at Kobe University in Japan describe how bombardier beetles can survive being eaten by a toad by releasing a hot chemical spray that makes the hungry amphibian vomit.

Bombardier beetles are so named because, when threatened, they emit a boiling, irritating substance from their backsides with remarkable accuracy, to deter potential predators. They produce the caustic mixture by combining hydrogen peroxide, hydroquinones and chemical catalysts in a specially reinforced chamber at the base of their abdomen, which shields the beetle's own organs from the resulting explosive reaction.

The Japanese researchers fed two different species of bombardier beetles to captive toads. They were then able to confirm that the beetles used their weapon inside the toads by listening carefully for the explosive pop that accompanies each discharge.

Toads are ambush predators, quite used to swallowing first and asking questions later. When they start to feel a dose of diner's remorse, they can literally turn their stomachs inside out and scrape out the contents, rather than suffering meekly from indigestion. Many of the toads in this experiment did just that, disgorging the beetles up to 107 minutes after ingestion. Remarkably, the ejected beetles all survived.

In a further experiment, the researchers poked beetles with forceps to deplete their spray reserves. Compared to those with full tanks of fuel, the exhausted beetles were much less likely to be ejected. This showed that it really was their chemical arsenals that saved them, rather than just their taste or behaviour in the gut.

The bombardier beetle is of course not the only animal escape artist. The diverse getaway tactics of animals are a testament to the fascinating creativity of evolution. Subject to millions of years of abuse and exploitation by predators, natural selection has shaped an array of ingenious strategies for cheating death in the face of would-be devourers.

Animal Houdinis

Some examples are probably familiar to most people. For instance, many lizards drop their tails to distract a predator or escape from its venom. But others are more exotic. Sea cucumbers don’t have tails so they eject and regenerate their internal organs instead. Loud sounds (such as the "gunshots" of snapping shrimp) and bright colours (as on band-winged grasshoppers) are also effective means of startling predators. Mantid insects unite movement, sound and colour in an elaborate display that can stop an attack or at least give them a chance to escape.

Some animals fight back, such as the frogs that can erect sharp bony splinters from their claws that pierce their own skin, like X-Men's Wolverine. Other animals, including the mimic octopus, prefer to pretend to be dangerous, adopting the appearance of more deadly prey when threatened.

The stunning variety of defensive mechanisms would be impressive even if we only counted variations of chemical warfare, similar to the bombardier beetle's steam treatment. There are the defensive toxins in pufferfish and poison arrow frogs, the nauseating odours of skunks, the charmingly named but actually revolting repugnatorial glands of some millipedes, and the projectile vomiting and faecal egg decorating of some birds.

Why should nature have created such an impressive array of defensive tactics? One possible explanation can be summarised as the life-dinner principle, articulated by biologists Richard Dawkins and John Krebs in the late 1970s. The argument is that predator and prey often face asymmetrical selection pressures, meaning that the stakes are different for the two competitors. If a predator fails to capture its target, it loses dinner, but if the prey fails to escape, it loses its life. Because the stakes are greater for prey, we shouldn't be surprised they have developed so many impressive defences.

Understanding nature's tremendous capacity to adapt should make us be careful. Humans interact with other organisms all the time, and usually we're the predators. When we try to take action against other creatures to stop them spreading disease or eating crops, we should be mindful that evolutionary innovation can produce remarkable adaptations. For example, our widespread use of antibiotics and pesticides has spurred the evolution of organisms that are resistant to these methods.

Only by having a healthy respect for the relentless power of evolution can we hope to generate sustainable solutions to these kinds of problems. If we grow complacent and inattentive, we may some day soon find ourselves facing newly evasive diseases and pests, sputtering to breathe and dyspeptic amid all the fire and smoke in our bellies.

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Top header image: Andrew/Flickr

Luc Bussiere, Lecturer in Biological Sciences, University of Stirling

This article was originally published on The Conversation. Read the original article.

Jurassic Park may be the first thing that comes to your mind when you hear about this subject – any time an ancient DNA news story surfaces, comments sections are sure to include questions about cloning or resurrecting extinct species – but there's more to this science than dreams of de-extinction (more on that topic later!): ancient DNA opens doors to answering many of palaeontology's perplexing questions, and has dramatically changed how scientists investigate the past.

Long-held secrets

Last summer, a study triumphantly announced that ancient DNA had solved the mystery of Macrauchenia, a bizarre South American mammal whose place on the mammal family tree had been a palaeontological puzzle ever since the days of Darwin. Several months later, another group of palaeo-geneticists presented a new name for the curiously stilt-legged extinct horses of the ancient Americas: Haringtonhippus.

If you follow palaeontology news, these are familiar sorts of stories. Most of what we know about fossil animals comes from skeletons, but bones and teeth aren't always enough to answer our questions about prehistoric life. Over the years, ancient DNA has built up a bit of a reputation for revealing secrets that bones alone could not.

"Bone morphology can be influenced by environment and behaviour," explained Leigha Lynch of Oklahoma State University over the phone. This variability is great for adaptable animals, but it can also make for a confusing time trying to discern the true identities and relationships of ancient species.

In her own research, Lynch turns to DNA for assistance. She studies North American martens – small carnivores related to weasels – ranging in age from several decades to 15,000 years old. Not only does their DNA help her sort out the relationships between the animals' various ancient populations, but by constructing the extended marten genealogy, she can also identify the location and timing at which new populations arose and new traits evolved. Combining this evolutionary info with the geologic record, she can then piece together how the animals responded to environmental changes such as Ice Age glacial cycles.

Animals' bodies also change as they grow, which can be another potential source of confusion when examining fossils. "[Sometimes] we don't know if we're looking at an adult or a juvenile or a new species. So being able to get the DNA to clarify that is really helpful."

A creature's chromosomes can also reveal its sex, a boon in those cases where males and females are so physically different they might be mistaken for separate species (think elephant seals!).

Ancient DNA can even help us understand extinction. A recent study of Tasmanian tigers found unexpectedly low genetic diversity in these animals going back thousands of years – a tell-tale sign of a long-term population decline that may have set the species up for its eventual human-induced disappearance.

(Fun fact: we can even get DNA from fossilised poop! One group of scientists, for example, was able to determine the diet of giant flightless moas from New Zealand in part by testing the DNA of the plants in their droppings!)

Faded genes

"Ancient DNA gets degraded over time," explained Viviane Slon of the Max Planck Institute for Evolutionary Anthropology in a phone call, "so not every fossil will yield DNA, and not every fossil will yield enough DNA to reconstruct a full genome." (A genome is the complete set of genes of an organism.)

A dead cell is a hostile environment for DNA, full of enzymes whose very job is to break down genetic material. In a still-living organism, this is important for DNA replication, repair and recycling, but once the whole organism dies, it means that DNA begins to deteriorate very quickly. The best environments for preserving DNA tend to be cold, dry and stable over long time periods, including permafrost, some caves, and – for more recent specimens – environmentally controlled museum collections.

The oldest DNA sequence ever recovered comes from a 700,000-year-old horse from the frozen soil of northern Canada, and this might be about as old as we can hope for. Research indicates that DNA degrades to a non-usable point after one or two million years, even under perfect conditions (which are rare or non-existent in nature).

One-million-year-old DNA is extremely impressive ... although it leaves out the vast majority of the 3,500-million-year history of life on Earth.

So, no Jurassic Park. The last of the non-bird dinosaurs went extinct 66 million years ago. And yes, even the scientists are disappointed.

"I love the idea – in theory, I could have a little Triceratops hanging out in my backyard," Lynch said. "[But] I find it very hard to picture any scenario in which DNA was preserved in something that old."

Even in relatively young fossils, DNA can disappear very quickly in an unfriendly environment. The cold, dry Arctic is great for its preservation, but the warm, wet tropics are just the opposite, typically preserving very little genetic material. So the fossil record of ancient DNA is much more likely to give us information about, say, woolly mammoths than about island tortoises.

But when conditions are right, DNA can preserve spectacularly well. In fact, one of the biggest challenges facing researchers is that there's often too much of it: a fossil horse bone might retain some original horse genes, but it's likely to also have DNA from the bacteria and insects that have gotten into the bones, or the plants and fungi that grew around it (and it will pretty much always end up with DNA from the humans who excavated it). That means researchers have to pick through a lot of "noise" to get out the specific DNA they want.

For Slon, this is especially tricky: she studies ancient humans (and our relatives like Neanderthals), so her fossils include both ancient and recent human DNA. "You're always going to get contaminant. The trick is to be able to tell them apart," she explained. "And you're going to do that by taking advantage of a particular type of chemical damage [called deamination] that accumulates over time in DNA." Knowing how to identify this damage helps scientists separate the old DNA from the new.

Slon and her colleagues have also found a way to take advantage of DNA's tendency to contaminate its surroundings. She recently led a study that discovered ancient human DNA in cave sediment. Studies like this are very encouraging for palaeontologists because they suggest that we can explore the DNA of ancient organisms without even needing their fossils!

The take-home point here is this: ancient DNA has limits. It comes with a host of challenges, it only lasts so long, and only in certain environments. But when researchers do find it, modern techniques allow them to piece together an astonishingly complete picture. "In a fossil that is well-preserved," Slon said, "we can get a genome that is equal in quality to genomes that we get today, if you put enough sequencing effort into it."

Is extinction truly forever?

In 1990, Michael Crichton published the novel Jurassic Park, but he was not the first to explore the idea of bringing ancient species back from the dead using DNA. In fact, the idea has been bouncing around for a long time, and there are some scientists today who are working on doing something very much like that.

In Jurassic Park, the dinosaurs were essentially cloned from ancient DNA, but real-life cloning – such as in the case of Dolly the sheep or the recent monkey twins – only works with viable cells, which the fossil record doesn't preserve. (Famously, preserved cells of the recently extinct bucardo, a wild goat native to the Pyrenees, were used to create a short-lived revenant in 2003.)

"The technology that lets us preserve viable cells in a freezer is only about 50 years old," said Ben Novak, lead researcher at Revive & Restore, over the phone. "Anything that goes extinct prior to that, we have nothing viable from."

Revive & Restore is an organisation that aims to use genetic technology to aid struggling species and ecosystems, from collapsing coral reefs to unhealthy black-footed ferrets. Among their most ambitious missions is the de-extinction of the passenger pigeon.

Before their extinction due to human activity in the early 1900s, passenger pigeons soared over eastern North America in flocks billions strong. Research has shown that these birds were major environmental influencers; a visiting flock of pigeons would cause a huge disturbance in a forest, creating a similar rejuvenating effect to that of a forest fire. Their disappearance left the forest ecosystems far less able to maintain healthy and stable conditions.

Novak and his colleagues want to bring those populations back with some help from the passenger pigeon's closest living relative: the band-tailed pigeon.

"Ninety-seven percent of the passenger pigeon's genome is still alive in the band-tailed pigeon, because that's how identical they are," Novak explained. The plan is to peruse the passenger pigeon genome for the features that made the species unique – those traits that allowed them to maintain huge flocks across North America – and edit them into the band-tailed pigeon, ultimately engineering a population of birds that can serve the same role as their extinct predecessors. 

This is de-extinction, but it's not exactly bringing a species back from the dead. "If we're going to get really technical, it [would be] a bird that is the genetic offspring of band-tailed pigeons and passenger pigeons," Novak said. "If that had been produced through natural breeding, we would call it a hybrid."

The goal here isn't to resurrect exactly what existed before, but to restore ecosystems to a healthy state by replacing a lost keystone species. Novak likens it to the reintroduction of wolves to Yellowstone: the predators had disappeared from this area, and a new wolf population was introduced to fill in that missing piece of local ecology. The passenger pigeon project simply takes more genetic innovation.

There are other species on the de-extinction radar, including the heath hen, which went extinct in the northeastern United States in 1932, and more famously the woolly mammoth, which has been extinct for thousands of years. These projects are in the exciting early stages, and may eventually play major roles in environmental conservation, but researchers are keen to remind us that we can never fully recreate the past.

"There's inevitably always something lost in extinction," Novak said, "things we don't know; things we can never know."

Our own past and future

"I think for me," said Slon, "the most amazing discovery of the last few years was the Denisovans."

In 2010, researchers sequenced the DNA of a very human-like finger bone in Denisova Cave in Siberia. The results were a surprise. It wasn't Homo sapiens and it wasn't Neanderthal; it was a closely related group that no one had ever seen. To this day, the only fossil remains known from this population – known as the Denisovans – are three teeth and one finger bone, and without ancient DNA we never would have realised they came from a totally separate lineage of ancient people.

From those bones, Slon and her colleagues have learned an immense amount of information about the Denisovans and their relationships. We know now, for example, that modern humans carry traces of not only Neanderthal DNA, but also that of the Denisovans.

"We know that Denisovans and Neanderthals must have mixed," Slon said, "and also Denisovans and modern humans mixed." More than perhaps any other species on Earth, the science of ancient DNA has taught us about ourselves.

Ancient DNA is an amazing resource for scientists aiming to learn about – and learn from – the past, and researchers are looking forward to a future filled with untold possibilities. Right now there are labs all over the world working at refining, improving and advancing the science of pulling DNA out of the past.

For city dwellers, especially those in the developed world, the idea of being bitten by a venomous snake seems outlandish. But it is a daily and very real risk for millions around the world – and that includes many people living in African countries.

Over one million snakebites occur annually in sub-Saharan Africa alone. These cause over 20 000 deaths and leave 60 000 people permanently disabled or disfigured. So approximately every hour in the region 115 people are bitten, seven suffer permanent damage, and three die.

Snakebite can cause a variety of clinical symptoms. These include paralysis, necrosis and bleeding, among others. Snake venoms contain a myriad of highly diverse toxins that manifest in very different ways clinically. This means there’s no single “magic bullet” treatment. Even so, there’s no doubt that antivenoms are crucial in the fight against snakebites.

The World Health Organisation (WHO) is spearheading a global effort to get effective and affordable antivenoms to parts of the world that really need them. It is doing this in several ways, including through strict pre-testing for antivenoms whose manufacturers want to release them commercially.

Such coordinated international efforts may be key to improving the life expectancy and health of many snakebite victims.

The impact of bad antivenoms

The only specific treatment for snakebite envenoming (the injection of venom by a snake) is to intravenously administer antivenom to a victim. Antivenoms are made by immunising a larger animal, like a horse, with increasing doses of snake venom. This triggers a reaction in the animal’s immune system, increasing the production of specific antibodies against the venom toxins. The antibodies are then extracted from the horse’s plasma and formulated into the final antivenom product.

Because snake venom differs from snake to snake, even within the same species, the neutralising ability of an antivenom must be carefully assessed before a fresh batch can be released and used on patients.

Until recently there was no external process or committee established to assess antivenom manufacturers’ preclinical testing. This was because these processes required a major investment of time and money. The result has been that not all antivenom products have lived up to expectations while in some cases they haven’t met some regions’ actual therapeutic needs. In sub-Saharan Africa, for instance, low quality antivenoms have been on sale.

This has been a major problem because certain antivenoms had little or no therapeutic value and can even cause harm, such as triggering allergic reactions and serum sickness. A case in point was the decision taken by Ghana’s health ministry to switch from using Fav-Afrique – one of sub-Saharan Africa’s most effective snakebite antivenoms – to the cheaper antivenom AsnaAntivenomC in 2004. This led to a 10-fold increase in mortality (from 2% to 12%) because the new antivenom was inefficient.

In Chad, the use of inefficient antivenom drove the snakebite death rate up to 15%.

Fixing the problem

News that Fav-Afrique was set to expire in 2016 caused dismay among public health experts and advocates, and received a great deal of media coverage. The WHO decided to step in.

In December 2015 it implemented a pre-qualification scheme for antivenoms. This scheme involves antivenom manufacturers assessing all aspects of their anti-venom production before submitting a dossier to the WHO, which then assesses if the antivenom lives up to the required standards.

Each production facility and manufactured antivenom is assessed by the WHO. Antivenoms with a favourable risk‒benefit ratio are then entered into a list of prequalified antivenoms on the WHO website.

This list can easily be accessed by procurement agencies. To date, 90 antivenoms from 45 different manufactures have been listed publicly on the site.

This is an important step because it offers a database from which organisations such as Doctors Without Borders and national health ministries can make educated choices about which antivenom would be the most relevant, safest and most economical.

There is precedent for schemes like this. In 2001, the WHO launched a prequalification scheme for AIDS medicines. This has been hugely successful suggesting that the antivenom prequalification scheme could make a real difference to millions of snakebite victims.

A step further

In 2017 the WHO took its attention to snakebite a step further: it re-added snakebite envenoming to its list of neglected tropical diseases. It is expected that this will add impetus to antivenom development and boost the likelihood of investor funding for snakebite prevention and treatment access initiatives.

For example the Ministry of Health in Kenya is developing local guidelines on snakebite management and plans to engage local and international donor health agencies.

The WHO has recently established a working group on snakebite envenoming that aims to develop a strategy for prevention and treatment of snakebite. Finally, snakebite is on the World Health Assembly’s agenda for the first time this year, receiving support from the Kofi Annan Foundation.

These are all developments worth celebrating. But it is important to continue pushing so that more can be achieved and snakebite deaths can, ultimately, become a thing of the past.

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Andreas Hougaard Laustsen, Associate Professor at the Department of Biotechnology and Biomedicine, Technical University of Denmark and Timothy Patrick Jenkins, Doctoral student at the Department of Veterinary Medicine, University of Cambridge

This article was originally published on The Conversation. Read the original article.

It's long been known that the turkey vulture – "buzzard," in widespread North American vernacular, not to be confused with the many Old World hawks called by that name – tracks down carcasses by smell, and that the cousin with which it most overlaps, the black vulture, is a more vision-reliant forager. The new research, published this past December in Scientific Reports, confirms through anatomical analysis that the turkey vulture does indeed boast quite the sense of smell – not only compared with the black or other vultures, but birds in general.

Along with a pronounced nasal cavity, turkey vultures possess a large olfactory bulb, a portion of the forebrain in vertebrates dedicated to scent. The Scientific Reports study aimed to take a deeper look at this structure. As Alicia Ault explained in a Smithsonian summary of the work, "Like the post-apocalyptic living dead roving the earth in zombie films, scientists needed fresh brains to determine exactly what was going on inside the turkey vulture's enlarged olfactory bulb."

The source of those fresh brains? A clutch of both turkey and black vultures legally culled by the United States Department of Agriculture in Nashville, Tennessee. After dissection, the researchers measured the relative volume of the olfactory bulb and, within, the number of mitral cells – which relay information collected by olfactory receptors to other parts of the brain – as well as the size of structures involved in the visual system. The volumetric measurements and mitral-cell count were compared with a wide variety of other bird species.

Turkey vultures claimed an olfactory bulb four times the size of black vultures' and twice as many mitral cells, even though the black vulture's brain is 20 percent larger. When judged against 143 other species of birds, the turkey vulture claimed the biggest olfactory bulb relative to brain volume. Compared with more than 30 other birds, meanwhile, turkey vultures also had the most mitral cells, though the researchers note this is likely simply a reflection of the outsized olfactory bulb.

Old World vultures – whose superficial resemblance to the vultures of the Americas is more a case of convergent evolution than taxonomic relation – are thought to locate carrion by sight alone, which likely explains why they're pretty much exclusively birds of open country. Among the New World clan, turkey vultures as well as their close Neotropical relatives, the greater and lesser yellow-headed vultures, are known for their ability to locate carcasses hidden in heavy forest – a reflection, it seems, of a potent sense of smell lacked by the other New World vultures: the black, the king and the two condors (California and Andean).

The authors of the Scientific Reports study note that turkey and black vultures diverged in the mid-Miocene, when a wide variety of large mammals flourished in North American savannahs and thus provided an ample supply of dead meat – and ample opportunity for vulture-on-vulture competition.

"Through the enlargement of its olfactory system, the turkey vulture was able to occupy a new sensory niche among vultures that depended on olfaction," they write. Today, the turkey vulture enjoys the largest range of any New World vulture – in fact, the largest range of any vulture in the world.

Turkey and black vultures continue to vie for (and rub shoulders around) carcasses from the southeastern US to central South America, pursuing different methods of scavenging. Turkey vultures tend to soar lower in the sky, the better to detect fetid wafts drifting up from critter corpses; black vultures cruise higher to boost their sightlines. Turkey vultures often forage alone or in small groups, whereas black vultures usually patrol en masse. Black vultures usually feed on larger carcasses, probably because those are the more visually conspicuous; turkey vultures can track down smaller, more obscure fare such as dead rabbits, snakes, birds and the like via olfactory detection.

One way black vultures get fed is by finding turkey vultures, which they typically displace from carcasses: generally speaking the black is more pugnacious and also tends to have numbers on its side. Thus the turkey vulture's superior sense of smell gives it a leg up in avoiding direct competition: it can (1) find carrion in thickly timbered country tough for an eyesight-oriented black vulture to forage in; (2) sniff out smaller nibbles that escape a black vulture's notice (and which would fail to feed a big scavenging flock of them); and (3) reach meat faster, giving it a mealtime head-start before black vultures arrive and muscle it off the prize.

(Interestingly, the Scientific Reports study didn't find evidence for black vultures boasting a keener sense of sight than turkey vultures.)

This makes for interesting ornithology on its own, but it's worth connecting to a bigger, more ecological message: vultures as a whole, Old World and New, perform vital ecosystem services as efficient, first-on-the-scene scavengers. Take these raw-headed carrion birds off the job, and there'd be a lot more putrid meat lying around.

As Ault notes in her Smithsonian article, South Asia has lately offered a cautionary tale: a catastrophic collapse in vulture numbers in India in recent decades – ultimately tied to the use of an anti-inflammatory drug in livestock – led to a buildup of carcasses, contamination of drinking water and a flourishing of scavenging feral dogs, along with a resultant spike in rabies transmission to humans.

So perhaps even the more squeamish among us should say a word of thanks to the turkey vulture's supersized olfactory bulb, and the awesome corpse-finding abilities it confers.

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Top header image: Pixabay

A team of scientists recently took a close look at those, well, looks – specifically, the facial and chest (aka anterior) patterns of a grand, globe-spanning lineup of terrestrial carnivores – to explore possible explanations for their evolution.

Their study, published last month in Behavioral Ecology & Sociobiology, analysed photographs of 164 sharp-toothed mammals from across six families: the canids (dogs), felids (cats), ursids (bears), mustelids (weasels and kin), viverrids (civets and kin) and herpestids (mongooses). (The hyenids missed the cut due to the fact that there are only four hyena species – too few to effectively compare and contrast under the study's approach.)

Within each carnivore family, the researchers came up with scores for the complexity and contrast of facial and chest colour patterns, and assessed these against a slew of independent variables: from geographic overlap (sympatry) between related species to diet and relative levels of sociality. Those factors were chosen in order to explore several hypotheses linking the evolution of anterior fur markings with particular habits.

Certain findings seemed to square with some prevailing ideas. The notion that more social carnivores might sport more complex frontal patterns – perhaps to enforce individual recognition within the group – jibed with the results for the facial markings of mongooses and the chest markings of dogs.

Meanwhile, the researchers weren't exactly surprised to find a correlation between complex, high-contrast facial pizzazz in mustelids such as the zorilla and the possession of sprayable anal musk: as in skunks, such flashy markings could at least partly serve as a visual warning to potential predators that this critter comes armed and loaded.

Among the weasel crew as well as the viverrids and mongooses, facial pattern also seemed to be associated (in somewhat different ways) with pugnacity. Many carnivores with striped faces hole up in burrows or dens, and it's possible their conspicuous markings direct a don't-even-try-it message straight at potential antagonists as the carnivore in question backs into its lair.

For members of both the civet and mongoose families, a more complex facial pattern tended to square with a diet skewed towards mammals – possibly because the markings help conceal the carnivore as it stalks such especially keen-sighted prey.

Among the bears, the study found species that significantly overlapped in range with other ursids tended to show less variation in facial contrast. Perhaps, the researchers speculated, that helps bears more easily recognize others of their own kind. But the relatively small number of bear species (eight) makes it tough to draw firm conclusions. Only one bear exists in complete isolation from others across its entire range: the spectacled bear, the only South American ursid and, incidentally, notable for its fancy face.

And the cats? Well, they lived up to their whole independent, uncooperative image by offering no statistically significant results in the study: no positive associations between face or chest flourishes and the particular lifestyles under analysis.

The authors suggest their inquiry, boiled down, mostly underscores the probability that carnivore face and chest patterns evolve for multiple purposes, and that it's risky to "assum[e] that similar markings serve similar functions even within a single taxonomic order".

The lead author of the study, Tim Caro of the University of California, Davis, told Science’s Michael Price that another group of mammals well known for its splendid array of face and chest markings definitely warrants this sort of investigation. "The holy grail in colouration is primates," he said. "We're just beginning to lay the groundwork that will get us there."

These splotchy brown-and-yellow serpents – which, despite their common name, are actually boas and not pythons – spend much of their lives in the soil and leaf litter of Africa's warm forests. When predators come near, they show off their tails, which look – confusingly – very much like their heads. And when it's time for food, they dive into rodent burrows looking for their favourite meal: baby rodents.

But hunting babies comes with one major danger: the defensive parents of their chosen prey. During hunts, the snakes have been spotted suffering attacks from angry burrow guardians – and the bite of a rodent is no joke. The animals' big, sharp incisors can cause serious injury, and it's not unheard of for snakes to ultimately die as a result. But the Calabar species doesn't seem put off by the risk.

"[W]hen attacked or threatened, rather than fleeing, C. reinhardtii relies on passive-defensive behaviours, including coiling, hiding its head and elevating its tail (which is more brightly coloured than the rest of the body)," explains a group of Missouri-based researchers in a recently published study.

To find the secret of the snakes' resilience, the scientists scrutinised their skin. They measured its thickness, examined its microscopic structure and straight-up stabbed it with hypodermic needles (they did this with skin samples, not on living snakes!). They also performed similar tests on 13 other snake species from all around the world and with various lifestyles, including other boas, rattlesnakes, garter snakes and more.

The results? The skin of the Calabar python is like armour! Compared to other similarly sized snakes, the skin of this species is up to 15 times thicker, and its unique scale arrangement offers minimal weak points.

Their hides aren't totally puncture-proof, but it took way more force for those needles to punch through than for any other snake tested. And that means the teeth of angry mama rodents probably don't pose much of a problem.

How does the skin of the Calabar snakes achieve such durability while also being flexible? Part of that answer lies deep within their dermis, where bundles of collagen are arranged in highly organised criss-crossing layers. This is the same feature that makes rhino skin so tough. In fact, the researchers called the Calabar python "the rhinoceros among serpents".

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Top header image: Screengrab (Science Magazine/YouTube)

Earlier this month, the World Health Organisation (WHO) reported some troubling news. On September 20, a man from Kween District in eastern Uganda was admitted to a local hospital after developing fever, bleeding, vomiting and diarrhoea. According to WHO, the man, a 35-year-old herdsman, frequently hunted near an area known to host bat-inhabited caves. He died five days later, after being transferred to a nearby hospital, but no blood samples were collected at that time and his death was not attributed to a specific disease.

Some three weeks later, his sister, who had cared for him and helped with burial rituals, was hospitalised with similar symptoms and died shortly after. Posthumous samples confirmed the presence of Marburg virus, a microbe that can infect both animals and humans. Shortly afterward, the Ugandan Ministry of Health declared an outbreak of Marburg virus disease (MVD) in Kween District.

But the story didn’t end here. A brother of these two also was diagnosed with MVD — but before he died, the man travelled to Kenya, potentially spreading the virus. Ugandan and Kenyan health authorities, WHO, UNICEF and the Kenya Red Cross Society are watching for evidence of further dissemination of this virus.

The outbreak, which may have begun when the first man was infected by a bat carrying the virus, is an example of a disease outbreak of zoonotic origin — one that can be transmitted from animals into humans. It appears that this incident has been limited to a local spillover of an animal-borne virus into humans. But the international travel component is a very real reminder that such a course of events can lead to a zoonotic pandemic, a worldwide spread of a pathogen — most often a virus — transmitted from animals to humans. From severe acute respiratory syndrome (SARS) to AIDS and Ebola, zoonotic diseases cause more than a billion cases of illness each year. As humans increasingly encroach on wildlife territory and increasingly travel long distances in short times, the threat of zoonotic pandemics is growing. At the same time, so are efforts to prevent or curtail them.

Recipe for a pandemic

Viruses have been moving between organisms for millions of years. And not always in a way that causes harm: animals and humans alike host millions of different microorganisms, many of which are beneficial.

“We live in an essentially microbial world, and we are actually complex ecosystems comprising a whole lot of microorganisms,” says Fabian Leendertz, head of the Epidemiology of Highly Pathogenic Microorganisms group at the Robert Koch Institute in Berlin. “Some are pathogenic, but most of them live at peace with us.”

For those that do harm humans, the first step is to come in contact with us. And that’s becoming more and more likely as we invade pristine forests in search of food, building materials, space for commercial developments or land upon which we can create new grassland for our livestock — or catch critters for bushmeat, pets or the “wildlife selfie” trade.

“The typical formula for a zoonotic outbreak starts with a human getting into contact to a viral host, like a bat or rodent. Then just a dash of luck that specific host carries [a] virus capable of jumping species barriers, and the epidemic starts from here,” Leendertz says.

Sometimes a zoonotic virus can jump directly into humans, as occurred with the Marburg virus. Other viruses, like the virus responsible for SARS, first spill over from a wildlife species into a domestic animal host, where the virus multiplies and evolves to become better able to infect a human host.

Once a zoonotic virus infects a human, different things can happen. If it is extremely virulent, it will rapidly kill its human host — which from a strictly epidemiological perspective can be seen as beneficial, because there may be fewer chances that the virus will spread to others. But if the virus takes some time before it makes the person sick and is easily transmitted from one person to another, a larger problem could occur.

“All you need then is for host to interact with more people, to move around and pass along the virus,” says Leendertz. “Before we even know about the virus, we can end up with a full-blown epidemic on our hands. This was the case with the HIV epidemic.”

Detection and discovery

What can be done to reduce the likelihood that new zoonotic viruses will emerge? And how can we become better prepared to deal with those that do? 

The PREDICT project, led by the One Health Institute at the School of Veterinary Medicine at the University of California, Davis, has been working since 2009 to identify viruses in wildlife such as bats, rodents and nonhuman primates around the world. The goal is to find viruses with potential for zoonotic outbreaks before they become a pandemic. The hope is that learning about these viruses will help governments design policies that can better deal with outbreaks.

The project is a worldwide collaboration, including scientists, government personnel, physicians, veterinarians, biologists, laboratory technicians, students and members of the general public from across 35 countries in Asia and Africa.

In the first phase of the PREDICT project, completed in 2014, researchers collected blood and tissue samples from wildlife and humans from across the world. These samples were tested for the presence of viruses with the goal of understanding where and how viruses spread from other animals into humans.

According to Tracey Goldstein, co-lead for PREDICT’s viral detection and discovery team based at UC Davis, as of October 2017 PREDICT had detected 1,044 distinct viruses present in wildlife and humans, of which 864 were newly discovered. It’s hard to say which of these new viruses can cause us harm, but the PREDICT team has compared their DNA sequences with those of known pathogenic viruses in order to identify potentially dangerous viruses. “About 5 percent of the new viruses have been prioritised​ so far for further study to understand their potential of causing disease in humans. The number of viruses we would like to understand better are likely to increase as we detect more of them,” Goldstein says.

But what matters most is not how many viruses were found, but where. “We have detected some of these viruses in more than one country or in more than one host species,” Goldstein says. This information ought to help PREDICT identify what countries should be considered high risk for viral spillover from animals to humans. This information may help policy-makers and others develop improved and more targeted surveillance, detection and prevention guidelines to address specific threats.

By comparing the DNA sequences of known pathogenic viruses with those discovered by PREDICT, researchers found that potentially harmful viruses are widespread across the globe. In Malaysia, for example, they found a new enterovirus species in a Bornean orangutan. Also found harbouring enteroviruses were five chimpanzees in the Democratic Republic of Congo and two mice in Cameroon. Enteroviruses are known to cause a wide range of symptoms in humans, from mild respiratory conditions to disorders of the central nervous system.

Coronaviruses related to the viruses responsible for SARS and Middle East respiratory syndrome (MERS) were found in Malaysia, Bolivia, China and Uganda, mostly in bats. One SARS-like coronavirus found in China called HKU3, was particularly troubling, PREDICT researchers say, because it shares many similarities with the human SARS coronavirus.

Several new members of the Rhabdoviridae family were found in Thailand, Indonesia, Tanzania and Republic of Congo, mostly in bat hosts. Some members of this family cause rabies or other types of fatal encephalitis in humans and other animals.

PREDICT has now moved into a second phase, PREDICT-2, with the scope broadened to include collecting samples from livestock as well as humans and wildlife. This new approach will serve to reveal viruses that already made the jump and are being shared by humans and other animals.

“This is the next step to better understand how viruses move between animals and people, as once you identify the viruses that have made the jump from wildlife into humans we can begin to understand what allowed this to happen and if they could be pathogenic,” Goldstein says.

PREDICT not only has identified viruses, it also has built infrastructure in many countries that allows for the detection and surveillance of zoonotic outbreaks. In these countries PREDICT has established protocols and trained personnel to identify viruses and handle animal samples safely. According to PREDICT, more than 3,500 individuals have been trained in the basic skills needed to respond to a zoonotic disease outbreaks in more than 35 countries across Latin America, Africa and Asia since 2009.

“Along with a more prepared workforce, many of these countries now have improved infrastructure and knowledge in place that allow for early detection of potentially zoonotic events that can enable more rapid response to new outbreaks,” says David John Wolking, global operations officer for the One Health Institute and member of the PREDICT team.

Global Virome Project

Another project that is currently in its initial phase is the Global Virome Project (GVP), first proposed in 2016 by a group of international stakeholders that included researchers, policy-makers and representatives from the public and private sector. This project seeks to detect and sequence the DNA of almost all viruses found in wildlife with potential to cause a human pandemic. Having a better understanding of the DNA makeup of viruses present in animals may help future studies identify viruses that are more likely to make the jump into humans.

Researchers involved with the development of the GVP are aiming to identify about half a million viruses, and estimate that it will cost around US$3.4 billion over the next ten years to complete their goals. The results of this ambitious project could serve as a valuable reference database for future studies focused on identifying the main drivers and other factors to better understand how zoonotic outbreaks may occur.

While the price tag may seem hefty, it is a fraction of the costs associated with responding to past zoonotic outbreaks, such as SARS (more than US$50 billion) or influenza (US$570 billion per year). And that’s just the beginning of the benefits, says GVP group leader Linfa Wang, director of the emerging infectious diseases program at Duke-NUS Medical School, a collaboration between Duke University and the National University of Singapore.

“In addition, the ambitious aim of GVP to create the atlas of viruses in the world will benefit not only those interested in emerging zoonotic diseases, but also the general scientific community in general, as it will also teach us new lessons in evolutionary biology, environmental impact, farming practice, urban development and more,” Wang says.

Policy and capacity

But what happens once we know about all the viruses we share with wildlife? Scientists hope the results from PREDICT will serve as the basis for future projects, studies and policies. For example, policy-makers can use PREDICT information to make decisions about how and where to invest healthcare resources. Likewise, wide-reaching institutions like the U.S. Centers for Disease Control and Prevention (CDC) can benefit from this information, because it might provide guidance on identifying countries representing a high risk of zoonotic outbreak.

Today, the CDC and USAID, through the Global Health Security Agenda launched in February 2014, are helping governments, international organisations, and non-governmental stakeholders build their technical capacity to respond to infectious diseases in over 50 countries.

The details on the whereabouts of novel viruses is a crucial component of this complex team effort. Thanks to these efforts, countries like Uganda, Vietnam and Ethiopia now have a network of laboratories with diagnostic capabilities and personnel trained in optimal emergency responses to disease outbreaks.

These capabilities have already been shown to be beneficial: they helped contain the recent Marburg outbreak in Uganda.

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Top header image: Pixabay

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To breathe or not to breathe, that is the question.

What would happen if you were submerged in a pond where the water temperature hovered just above freezing and the surface was capped by a lid of ice for 100 days?

Well, obviously you'd die.

And that's because you're not as cool as a turtle. And by cool I don't just mean amazing, I mean literally cool, as in cold. Plus, you can't breathe through your butt.

But turtles can, which is just one of the many reasons that turtles are truly awesome.

Cold weather slow down

As an ectotherm – an animal that relies on an external source of heat – a turtle's body temperature tracks that of its environment. If the pond water is 1℃, so is the turtle's body.

But turtles have lungs and they breathe air. So, how is it possible for them to survive in a frigid pond with a lid of ice that prevents them from coming up for air? The answer lies in the relationship between body temperature and metabolism.

A cold turtle in cold water has a slow metabolism. The colder it gets, the slower its metabolism, which translates into lower energy and oxygen demands.

When turtles hibernate, they rely on stored energy and uptake oxygen from the pond water by moving it across body surfaces that are flush with blood vessels. In this way, they can get enough oxygen to support their minimal needs without using their lungs. And turtles have one area that is especially well vascularised: their butts.

See, I wasn't kidding, turtles really can breathe through their butts. (The technical term is cloacal respiration.)

Not frozen, just cold

We are not turtles. We are endotherms – expensive metabolic heat furnaces – that need to constantly fuel our bodies with food to generate body heat and maintain a constant temperature to stay alive and well.

When it’s cold out, we pile on clothes to trap metabolic heat and stay warm. We could never pick up enough oxygen across our vascularised surfaces, other than our lungs, to supply the high demand of our metabolic furnaces.

For humans, a change in body temperature is a sign of illness, that something is wrong. When a turtle's body temperature changes, it's simply because the environment has become warmer or colder.

But even ectotherms have their limits. With very few exceptions (e.g., box turtles), adult turtles cannot survive freezing temperatures; they cannot survive having ice crystals in their bodies. This is why freshwater turtles hibernate in water, where their body temperatures remain relatively stable and will not go below freezing.

Water acts as a temperature buffer; it has a high specific heat, which means it takes a lot of energy to change water temperature. Pond water temperatures remain quite stable over the winter and an ectotherm sitting in that water will have a similarly stable body temperature. Air, on the other hand, has a low specific heat so its temperature fluctuates, and gets too cold for turtle survival.

Crampy muscles

An ice-covered pond presents two problems for turtles: they can't surface to take a breath, and little new oxygen gets into the water. On top of that, there are other critters in the pond consuming the oxygen that was produced by aquatic plants during the summer.

Over the winter, as the oxygen is used up, the pond becomes hypoxic (low oxygen content) or anoxic (depleted of oxygen). Some turtles can handle water with low oxygen content – others cannot.

Snapping turtles and painted turtles tolerate this stressful situation by switching their metabolism to one that doesn't require oxygen. This ability is amazing, but can be dangerous, even lethal, if it goes on for too long, because acids build up in their tissues as a result of this metabolic switch.

But how long is "too long"? Both snapping turtles and painted turtles can survive forced submergence at cold water temperatures in the lab for well over 100 days. Painted turtles are the kings of anoxia-tolerance. They mobilise calcium from their shells to neutralise the acid, in much the same way we take calcium-containing antacids for heartburn.

In the spring, when anaerobic turtles emerge from hibernation, they are basically one big muscle cramp. It's like when you go for a hard run – your body switches to anaerobic metabolism, lactic acid builds up and you get a cramp. The turtles are desperate to bask in the sun to increase their body temperature, to fire up their metabolism and eliminate these acidic by-products.

And it's hard to move when they're that crampy, making them vulnerable to predators and other hazards. Spring emergence can be a dangerous time for these lethargic turtles.

Cold weather turtle tracking

Field biologists tend to do their research during the spring and summer, when animals are most active. But in Ontario, Canada, where the winters are long, many turtle species are inactive for half of their lives.

Understanding what they do and need during winter is essential to their conservation and habitat protection, especially given that two-thirds of turtle species are at risk of extinction.

My research group has monitored several species of freshwater turtles during their hibernation. We attach tiny devices to the turtles' shells that measure temperature and allow us to follow them under the ice.

We've found that all species choose to hibernate in wetland locations that hover just above freezing, that they move around under the ice, hibernate in groups and return to the same places winter after winter.

Despite all this work, we still know so little about this part of turtles' lives.

So, I do what any committed biologist would do: I send my students out to do field research at -25℃. We are not restricted to fair-weather biology here.

Besides, there is unparalleled beauty in a Canadian winter landscape, especially when you envision all of those awesome turtles beneath the ice, breathing through their butts.

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Top header image: Pixabay

Jacqueline Litzgus, Professor, Department of Biology, Laurentian University

This article was originally published on The Conversation. Read the original article.

But getting accurate statistics is incredibly difficult. Many bites go unreported, with as few as 8.5% of snakebite victims seeking medical treatment. In Africa, snakebite probably kills over 30,000 people per year. This is proportionally more than in most other regions around the world. A large percentage of these deaths can be attributed to one genus of snake: Echis.

Also known as the saw-scaled viper, Echis can be found throughout sub-Saharan Africa north of the Equator and in parts of Asia and the Middle East. This small viper dominates snakebite statistics and kills more people annually than any other. For example, Echis ocellatus is responsible for as many as 95% of snake bites in northern Nigeria.

Many of the toxins in the viper's venom target the blood to induce clotting. For humans, this causes a potentially lethal condition called "venom-induced consumption coagulopathy", more commonly called VICC. This disrupts the body's ability to regulate blood flow and results in severe internal bleeding. Haemorrhage, stroke and shock are typically the cause of death following VICC. Antivenom is the only effective antidote.

But the continent is experiencing an antivenom crisis. This crisis is a result of the discontinuation of a key antivenom in Africa, Fav-Afrique. Fav-Afrique was very effective at treating snakebites in the region: some clinics reported a 100% success rate when using this antivenom. But the antivenom's manufacturers, Sanofi-Pasteur, stopped production of Fav-Afrique after claiming they were priced out of the market.

The disappearance of Fav-Afrique from African clinics partly explains the exceptionally high rates of snakebite death on the continent. It has seen an increase in the use of cheaper, Indian-produced antivenoms – many of which appear to be largely ineffective.

To investigate the issue further, we conducted a comparison of four antivenoms that are commonly used to treat Echis bites on the continent. Two were made using Indian Echis venoms and two made using African Echis venoms. We tested these antivenoms against venom samples from ten different populations of Echis across their distribution, from Africa to Asia.

Comparing antivenoms

We first added the venom to human blood plasma and measured the rate at which each venom induced a blood clot. We then repeated the experiment, but with an additional step. Before adding the venom to the plasma, we mixed the venom and antivenom. This step was to give the antivenom a chance to bind with the venom toxins and neutralise their harmful activity on the blood. We assessed the effectiveness of the antivenoms by looking at how well they were able to slow the clotting caused by the venom when compared to our first experiment.

What we found was alarming. Despite the antivenoms being marketed as species-specific (that is, able to treat the bite of a given species), we found extreme region-specific variability in their effectiveness. This means that the performance of the antivenoms varied based on the geographical origin of the venoms, even within a single species.

The Indian-made antivenoms, common throughout Africa because they are affordable, showed little to no neutralisation of the African Echis venoms. Even the venoms of some Indian Echis populations showed limited response to the Indian antivenoms.

Clinical case statistics support our findings. After switching to an Indian-produced antivenom following the discontinuation of Fav-Afrique, some African clinics have recorded a horrific 7 to 20-fold increase in case death rates.

Why such variability in the antivenoms?

Antivenoms are developed by injecting a small amount of venom from either one or from multiple species (to produce "monovalent" or "polyvalent" antivenom, respectively) into a host animal, such as a horse. The animal's immune system responds by producing antibodies that recognise and fight those venom toxins, much like what happens in our bodies when we get a vaccine. These antibodies are extracted and purified. The resulting antivenom is then marketed as being able to treat a bite by the species whose venom was used during its production.

This process is effective and reliable when venom composition does not differ much between individual snakes. Antivenoms may even be effective in treating the bite of a closely related snake species. Unfortunately, this is not the case for Echis as their venom composition varies between populations.

This is partly thought to be an evolutionary adaptation linked to diet. A key function of snake venom is to assist in prey capture. The toxins in venom do this by targeting specific parts of the prey's physiology, such as the blood or the nerves, to disrupt normal body function and immobilise the animal.

Different Echis populations feed on different prey types. For example, some feed mostly on vertebrates such as rodents or lizards, while others prefer invertebrates such as scorpions. The physiology of these prey animals differs, and this dictates what makes a toxin effective for predation. This could be why some populations have evolved different sets of toxins.

From a medical perspective, this means that the antibodies in an antivenom may not be able to adequately recognise and fight all the harmful toxins in the venom. The outcome for patients and clinicians is variable or reduced antivenom effectiveness between regions.

Our results show the failings that come from using a geographically restricted range of antivenoms and marketing them inappropriately. Given the seriousness of snakebite in Africa and around the world, this puts the pressure firmly on antivenom manufacturers to develop, market and distribute their antivenoms responsibly.

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Bianca op den Brouw, PhD Candidate in Toxinology, The University of Queensland

This article was originally published on The Conversation. Read the original article.

Top header image: Marathekedar93/Wikimedia Commons

It’s spring in Australia and that means reptiles are starting to move about again. Including snakes.

The venom of the eastern brown snake (Pseudonaja textilis) is, drop for drop, one of the most potent of any venoms tested on laboratory mice.

Venoms work by targeting the bitten animal with deadly chemicals. And our recent research shows toxins in the venom of eastern brown snakes change as the snakes grow from juveniles to adults. It’s the first example of a significant age-related change in venom from an Australian snake.

It’s a beautiful example of evolutionary adaption, in which the chemistry of the snake’s venom appears to change in parallel with its diet.

What is snake venom?

Venoms are typically a mixture of different toxins, each of which attacks the system of a potential prey animal or predator in a different way.

Sometimes toxins work together, each making the other more powerful, and sometimes they work completely independently, engaging in chemical warfare on multiple fronts.

Brown snake venom contains many toxins, but there is one toxin above all others that is responsible for the life-threatening effects of bites to humans. This toxin is a “haemotoxin”, which means it attacks the blood.

The haemotoxin starts clotting the blood at an extremely elevated rate, using up all of the coagulation factors, which clot the blood under normal circumstances. When all these are used up, the victim is at risk of bleeding to death.

In the worst case scenario, this toxin, perhaps working with others, gives the system such a shock that people collapse within a short period of time following the bite. In this situation, immediate CPR can be the difference between life and death.

Why venom evolved

Venom is a tool that has evolved in snakes to help them secure a meal: it gives them a chance of overpowering animals that would otherwise be very difficult for them to subdue. Venom and its toxins are therefore “designed” (by evolution) to mess up the normal operations of a prey animal’s body.

The best toxins for this purpose may differ according to the specific type of prey animal (e.g. mammal or reptile), or the condition of that prey animal (e.g. whether it is active or inactive) when the snake finds it. As a result, we often find snakes that feed upon different types of animals have different toxins in their venoms.

This starts to get really interesting when you consider brown snakes, because adult brown snakes seem to have quite different diets from baby brown snakes.

Testing a venom hypothesis

Age-related shifts in venom chemistry have already been demonstrated for the venoms of a few species of pit vipers from the Americas, but not for anything even remotely related to Australian brown snakes.

This wasn’t because people hadn’t looked – several species of Australian snake had been investigated, but no evidence of a significant age-related change in venom had been found for any of them. This made sense to me, because none of those snakes dramatically change their diets throughout their lives.

But brown snakes are special – as far as we know, the juveniles eat lizards almost exclusively, whereas the adults are generalists that eat a lot of mammals.

Baby snake venom is different

When we compared venom in adult and baby brown snakes, we did indeed find them to be different. Baby brown snake venom seems to entirely lack haemotoxins: instead, it’s almost exclusively composed of neurotoxins – toxins that attack nerve junctions.

What this suggests is that the haemotoxins that are so dangerous to humans (and lab mice) aren’t very effective against the lizards that baby brown snakes eat. We can make this dietary link with a degree of confidence because many other Australian snakes that feed exclusively on lizards have similar venom – no haemotoxins, only neurotoxins.

We don’t yet know what this means from a clinical perspective. It may be that baby brown snake venom is less dangerous to humans than adult brown snake venom, but the opposite might also be true – brown snake antivenom might be less effective against the venom of the babies.

There has been at least one fatal bite from a very small brown snake in Australia, so they must be treated with respect at any age.

As always, the best policy for snakes is to leave them alone and let them go about their business, and to teach children to do the same – snakes want no more to do with us than we want with them.

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Timothy N. W. Jackson, Postdoctoral Research Fellow, Australian Venom Research Unit, University of Melbourne

This article was originally published on The Conversation. Read the original article.

Top header image: DEPI Victoria/Flickr

The short answer is that water dissolves the salts contained in rocks, and these salts are carried in the water to the sea.

As raindrops form, they absorb carbon dioxide from the air. The water (H₂O) and carbon dioxide (CO₂) react to form carbonic acid (H₂CO₃), which makes rainwater slightly acidic, with a pH of around 5.6. (Pure water has a pH of 7, which is neutral.)

So, rain dissolves salts out of the rocks and these salts are carried via runoff to streams and rivers and finally to the sea. Rivers carry almost four billion tonnes of salt to the sea each year.

But rivers aren’t salty, right? Rivers are definitely not as salty as the sea, but they constantly carry their small salt content into the sea, and as a result the concentration of salt in the sea (which oceanographers call salinity) has built up over millions of years.

In fact, rivers aren’t the only source of sea salt. Rocks in the sea also play a role, and hydrothermal vents in the ocean floor and subsea volcanoes also supply dissolved salts to the sea.

Over millions of years, the concentration of salts has increased from possibly almost fresh in the primeval sea to where it is now – an average of 35 grams of salt in every kilogram of seawater.

If all this salt could be taken out of the ocean and spread over Earth’s land surface, according to the US National Oceanic and Atmospheric Administration, it would form a layer more than 150 metres thick.

Why are some places saltier than others?

Salinity varies from place to place in the sea, depending on how close you are to rivers, how much rain falls, how much evaporation occurs, and whether ocean currents are bringing in saltier or fresher water.

In general, the sea is saltier in the subtropics, where evaporation is high due to warm air temperatures, steady trade winds, and very low humidity related to atmospheric circulation patterns called Hadley Cells.

The sea is fresher close to the Equator where rainfall is high, and in the Southern Ocean and Arctic Ocean, where sea ice melt in the summer adds fresh water.

Enclosed seas, such as the Mediterranean and Red Seas, can be very salty indeed. This is because the removal of fresh water by evaporation is much larger than the addition by rainfall, and lower-salinity waters from the deep sea can’t flow in as easily.

Ocean salinity as a rain gauge

While the total amount of salt in the sea is pretty constant, the distribution of the salt is changing. Broadly speaking, the salty parts of the ocean are becoming saltier, and the fresh parts fresher.

These salinity changes are caused by changing rainfall and evaporation patterns globally, where wet places are generally becoming wetter and dry places are getting drier.

This amplification of the water cycle is a consequence of rising air temperatures due to climate change. Warm air can hold more moisture, so it can receive more evaporated water from the sea or land surface, and then release more when it rains.

Just how fast the water cycle is amplifying is a topic of current research.

Rainfall and evaporation are difficult to measure accurately, particularly over the ocean, where 78% of rain falls.

Ocean salinity, on the other hand, is easier to measure now that we have the global Argo programme: an armada of profiling floats that measure salinity and temperature from the surface to a depth of 2,000 metres, and surface salinity measurements via satellite.

Ocean salinity measurements are not only being used to understand past changes in the water cycle and reduce uncertainty in climate models, but are also helping to improve seasonal rain forecasts around the world.

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This is an article from "I Have Always Wondered", a new series where readers send in questions they'd like an expert to answer. Send your question to alwayswondered@theconversation.edu.au

This article was originally published on The Conversation. Read the original article.