Caecilian 10 05 2014
Image: Rog Qui, Flickr

From America to Zimbabwe, people across the world will celebrate Mother's Day in some form or other this weekend. In Australia, that means chrysanthemums. In Belgium, it's croissants. And for an order of amphibians known as caecilians, it means letting your babies strip the flesh from your body like a pack of ravenous hellsnakes. Good tradition, right?

To be fair, the caecilian maternal instinct isn't restricted to one weekend in May. While their young are developing, female caecilians of certain species feed their babes the skin off their backs – and bellies and sides and ... well, pretty much everywhere; caecilians are basically tubes. Kind of puts the whole "I was in labour with you for 37 hours in a blizzard!" story to shame, huh? (Sorry, Mom.)

But since the word caecilian (pronounced more or less like the pizza) probably isn't familiar to most people, we should back up a tick. Like I said before, the caecilians are an order of amphibians, which means they're classmates of frogs and salamanders. Though as you can see from the image above, they look more like snakes or worms than they do the other members of their class. And while the caecilians are easily the least popular branch of Amphibia, you could make an argument that they're the most interesting (interesting enough to write a song about). 

Caecilian Mother With Eggs 10 05 2014
A caecilian mother, from a species known for its skin-feeding ways, with her eggs. Image: Wilkinson M, Sherratt E, Starace F, Gower DJ (2013)

Caecilians are a remarkably diverse bunch. Like gummy worms, they come in many colours and configurations – from blue and purple to red, with both horizontal and vertical stripes. Some species spend the majority of their lives in water, others in the underbrush, and still others underground. But the thing you’re likely to notice first about caecilians is also one of the aspects that make them so unusual as amphibians: they have exactly zero legs.

Obviously, if snakes, worms and eels can get around sans legs, so can the caecilian, but it's how they do so that's interesting. Scientists have observed that some species have vertebrae capable of moving independently from the animal's skin and musculature. While underground, they use this ability to scrunch up the back half of their spine, a bit like a spring, which anchors their body to the tightly packed soil around them. With the back half anchored, the front half of the caecilian charges forward into the dirt like a freaking hydraulic ram.

Either because using your head as a pile driver is somewhat dangerous, or because subterranean creatures don’t have much use for vision, many species of caecilians have teeny tiny eyeballs. Others cover their eyes completely in layers of skin or lock them behind a layer of bone. (Caecilians, it seems, are all about giving things up. At least two species, one aquatic and one terrestrial, cancelled their subscriptions to lung-breathing through millions of years of evolution. They breathe through their skin instead.)

“Even though caecilians look like slimy, squishy lengths of saltwater taffy, they're actually quite formidable predators.”

Now that you know a bit about the caecilians in general, let's talk teeth. First of all, they have them. Because even though caecilians look like slimy, squishy lengths of saltwater taffy, they're actually quite formidable predators. Crickets, earthworms, ants, termites and other arthropods are all on the menu. Aquatic species can even take down small fish.

Once a caecilian grabs ahold of its prey, it launches into a series of 'long-axis rotations'. In other words, it goes into a death roll – not unlike a crocodile. Scientists have measured this chomping technique and found that it affords the predators with bite forces about ten times stronger than would be expected for an animal with the same body mass. Because caecilians often practise a bite-first-ask-questions-later approach to subterranean hunting, rapidly opening and closing the mouth throughout the death roll may also provide sensory information that helps them figure out exactly what they're attacking.

Baby caecilians know how to death roll, too. When a female is taking care of a brood, her skin becomes pale and her epidermal cells grow large with fat and other nutrients. Every few days the tiny terrors erupt all at once and turn into a writhing mass of hungry mouths. The feeding frenzy doesn’t appear to bother the female, though she will lose weight because of it over the next few weeks. It all goes something like this:


And that's just the egg-layer species. About three-quarters of caecilians give birth to live young ... and these mothers might deserve a day of celebration most of all. Their baby beasties develop small teeth while they're still foetuses. And why should a foetus need fangs before birth?

So it can munch on the mom’s reproductive organs, of course. Happy Mother’s Day!

Top header image: aposematic herpetologist, Flickr