Most of the year, these brilliantly coloured Sierra newts (Taricha sierrae) hide on land, eating bugs and hiding from their predators in the moist soil or beneath rocks and logs. But towards the end of winter they become aquatic, taking to the streams and pools of California's Yosemite National Park and elsewhere, in search of a good time.
Once they're in the water, their skin becomes smoother, their tails become more like rudders, and the males develop thick pads on their feet. Their beefed-up toes help the males to keep hold of the females while mating. As you might imagine, it can be tough to do the deed in such a slippery environment.
By the time the females arrive, the males have been there for weeks, so they're pretty lonely and ready for action. The amphibians cluster into mating balls (see 2:12 in the video), with multiple males each trying to grasp the female. Once a male wins, he swims away with her, leaving the rest of the males to search for another available female. The National Park Service explains: "[A]fter a male successfully grasps a female and swims away with her, he will deposit a spermatophore, which she carries to a suitable spot to fertilise and lay her eggs. Each spherical egg mass contains between 7 and 30 eggs and is attached to submerged vegetation or other underwater objects."
Their bright orange colouration serves as a warning to predators. Glands in their skin secrete a dangerous neurotoxin called 'tetrodotoxin', the same poison associated with pufferfish, sunfish, blue-ringed octopuses and a variety of worms, frogs and toads. Since the newts have been evolving in the Sierra Nevada Mountains for such a long time, they have only one real predator to worry about. Some garter snakes have evolved a genetic resistance to the toxin. As a result of being locked in an evolutionary arms race, the newts evolve ever more potent toxins, while the snakes evolve even better resistance. That means the tetrodotoxin that the newt produces (in truth, it's produced by by symbiotic bacteria that live inside the newts) is more powerful than it needs to be to subdue any other possible predator, but not quite powerful enough to drive away the snakes.
Once thought of as a sub-species of the California newt (Taricha torosa) researchers determined in 2007 that the Sierra newt has been evolving on its own long enough to warrant being classified as a species itself.
Top header image: fusatia/Flickr
