Caecilians

Originally published November 11, 2009 (The Manitoban, Vol. 97, No. 13)

While my long-term goal as a volunteer science writer does include developing a ravenous cult following at least the size of Winnipeg, I am not yet so megalomaniacal as to expect that just 5 articles spanning 3 months will have generated a base of regular readers. However, just in case any of you happen to be riding on the leading edge of my wave (so to speak), I want you to know that I really wish this article hadn’t taken so long. The thing is…I really wanted to talk about Archelon but to my utter dismay, I just couldn’t find enough information. 

This is what I could find out about Archelon: Archelon was a marine turtle alive during the late cretaceous period 80-odd million years ago that looked pretty similar to marine turtles alive today with the exception that it was the largest turtle that ever existed (as far as we know). 

Archelon was the size of a small car, but bigger than a Smart car because they don’t count.

So without further ado, I will now talk about caecilians because they are really cool too and they are not extinct. And unlike that nasty trick I pulled last time, they are not about to become extinct (largely because most of them live underground and no one really knows very much about them and with the exception of one species that is in fact endangered). I also won’t include any bad jokes about Sicilians but this is mostly just because I don’t know any, so if you have some that you find relevant, you can just add them in wherever you like. 

 

Caecilians! They, along with frogs and salamanders, are amphibians. They do not have limbs (i.e. they are legless), they are either aquatic or burrowing, some lay eggs but the majority are viviparous (give birth to live young), and many exhibit parental care. Some caecilians have scales (no other living amphibians have scales as far as anyone who’s talking about it knows) and all caecilians have tentacles, which are likely an adaptation to living under low-light conditions.

Some structures that are associated with eyes in other vertebrates are instead associated with tentacles and the eyes, which are reduced or even covered with thin flaps of skin, are located on the tentacle itself in some species. They are thought to have a chemosensory (“smelling”) function. Roughly 75 percent of known caecilian species give birth to fully formed young that may be between 30 to 60 percent of their mother’s body length (yikes). 

Initial growth of the fetus is supported by a yolk but this is used up before development has completed, meaning the remaining energy needed has to be supplied internally by the mother. Nutritious materials and secretions are scraped from the walls of the mother’s oviducts with specialized teeth! In caecilians which do lay eggs, the female often broods and guards the eggs until they hatch. 

If you are a geek like me and think that David Attenborough is just the cat’s meow, you may be familiar with a newish series called Life in Cold Blood. The film crew and science team were able to stick a fancy little camera into a caecilian’s burrow and made a really neat discovery: oviparous (egg-laying) caecilians must provide food for their under-developed young once they hatch and the spy camera found that mother caecilians begin to slough off a specialized outer layer of skin, high in fat and other nutrients, upon which the baby caecilians feed every 3 nights or so! Talk about giving the shirt off your back. 

The young show a 10-fold increase in growth in just a week of this, so even though it might sound disgusting, it is a great way fatten your kids up and get them the heck out of the house (or burrow as it were) already. Be sure to tune in next time for… something else obscure and intriguing and worth waiting for!