Before I even begin to talk about these creatures, I have to say that caecilians (which get their name from caecus, the Latin word for blind) are neither worms nor snakes nor even legless lizards – they are amphibians, relatives of frogs and salamanders. Most live in underground burrows in tropical rain forests, and there are several aquatic species. Though they look squishy and wormy, they do have bones and teeth. Their skull is hard and pointed so they can burrow through the ground. Though a layer of protective skin covers their eyes, they are actually sensitive to light and dark. Like other amphibians some caecilians have poison glands in their skin, and like snakes most have evolved to have an enlarged left lung with a reduced right one.
- Tentacles – yes, caecilians have (small) tentacles. They are located on the skull between the eyes and the nostrils, and in at least one species of caecilian the eyes actually protrude on the tips of the tentacles (like a snail’s). The tentacles are believed to be sensory organs that help it detect chemicals in the soil.
A tiny tentacle (not to mention an eye, a nostril, and the mouth) is visible in the head shot of a caecilian below.
- Feeding of the young – some caecilian mothers feed their young by growing a layer of fatty skin. The mother’s brood then use their specialized teeth to shear the nutritious skin off of their mother. BBC Video of feeding young
The BBC video has more feeding action (and an annoying narrator), but here’s a quick one of a caecilian feeding on its mother’s skin.
- Other stuff – Caecilians have quite a few other characteristics, which, if not unique, are at least interesting to know.
– Oviparity – some caecilians lay eggs, which can either hatch into gilled larvae or fully developed young.
– Viviparity – some caecilians give birth to live young, which can be either fully developed or altricial (still not fully developed and dependent upon the mother, like a human baby). Dermatotrophy (the eating of the skin) and matrotrophy (the eating of the oviduct lining) by young occur in caecilian species that give birth to altricial babies.
– Sex organs – male caecilians have unique sex organs, but the terminology involved in explaining it is pretty complex and not very interesting, so you’ll have to read this article to learn more about it.
Caecilian diversity – here’s a small sampling of some caecilians (you can find these just by doing a Google Image search)
Surreal caecilians part I: tentacles and protrusible eyes [Tetrapod Zoology] This source is extremely informative and well-written.
Surreal caecilians part II: pass mum’s skin, hold the mayo [Tetrapod Zoology] This article, like its prequel, is also very interesting and informative.
“Flesh-eating” amphibians filmed [BBC News] This article has a link to the video of the young caecilians eating the skin of their mother. I found the audio kind of annoying, but the video itself is very good.
Baby Caecilians Feeding [YouTube, from NewScientist] Interesting, but not very exciting.
Livingunderworld.org – Mexican Burrowing Caecilian (Image: Takeshi Ebinuma)
Wikimedia – Caecilian (Image: Wynaad, 2005)
Livingunderworld.org – I. bannanicus (Image: Nicolai Orlov)
Zooillogix (Scienceblogs) – New Caecilian Species Discovered in India (by ableiman, Image: source unknown)
Smithsonian National Zoological Park and the National Zoo – Aquatic caecilian (Image: Jessie Cohen)
E.D.G.E. – Sagalla Caecilian (Image: John Measy)
Birdspiders.com – Amphibian, Ringed Caecilian (Image: Rick C. West, 2005)
LiveScience.com – New Amphibian Tree of Life (Image: Taran Grant)
California Academy of Sciences – The Gulf of Guinea Expeditions (by bob, Image: source unknown)