Tuesday, 30 December 2014

9 Weird and Interesting Facts about Caecilians

There are about 200 species of caecilians (pronounced ‘seh-SILL-yuns’) but it's highly unlikely you have or will ever encounter one.  Why? Because they live underground, burrowing through loose soil and ground litter with their long, snake-like bodies.

Read on to learn 9 weird and interesting facts about these unusual creatures.

Bombay caecilian, one of the largest caecilians (Ichthyophis bombayensis)
Bombay caecilian (Ichthyophis bombayensis)
Credit - Wikicommons

1# They are actually amphibians
When you hear the word amphibian the first thing that pops into your mind is probably a frog, a toad or maybe a salamander. Caecilians may superficially resemble earthworms or snakes but they are a lesser order (Gymnophiona) of amphibians like frogs and salamanders.

2# They come in a variety of sizes..Some caecilians are very small, less then 7 cm and resemble worms while others are huge with lengths of more than 1 m and resemble snakes. The largest one is Caecilia thompsoni, commonly known as Thompson's caecilian. It reaches a length of 1.5 m (5 ft) and can weigh up to 1 kg (2.2 lb).

Pink Dermophis mexicanus caecilian
Dermophis mexicanus
Credit - Wikicommons

3# ..and a variety of colors
Most of them come in dark colors but some species have colorful vivid skins including purple, green, blue, orange and yellow. These bright colors may be a warning coloration to predators that their skin has poison glands.

4# Babies feed on their mother's skinMany say that being a mother is the toughest job. That is especially true if you are a Caecilian. In some species, the youngs stay with their mother for several weeks. During this time, the newborns feed on a specialized skin full of nutrients that their mother grows! Here's a video showing the process:

Baby caecilian eating its mother

5# They have teeth and strong jaws
Most caecilians have mouths filled with needle-like teeth and two sets of muscles for closing the jaw, compared with the single pair found in other animals.

The diet of caecilians is not well known but they seem to primarily feed on insects, earthworms and other invertebrates found in the habitat of the respective species. The larger species may also consume small snakes, frogs, and lizards.

6# They give birth to live young
About 25% of caecilian species are oviparous(egg-laying), but the rest 75% gives birth to already-developed offspring. The fetus uses its special scraping teeth to feed on the lining of their mother’s oviduct.

Pink Ichthyophis, unknown species
Ichthyophis Sp.
Credit - Wikicommons

7# Sex lasts for several hours
Male caecilians have a long tube-like organ, the phallodeum, which is inserted into the cloaca of the female for two to three hours. Caecilians are also the only order of amphibians to use internal insemination exclusively.

8# Most of them have very poor vision
Adapted to the underground life, the eyes are small and covered by skin for protection, which has led to the misconception that they are blind. This is not entirely true, although their sight is limited to simple dark-light perception. All caecilians possess a pair of tentacles, located between their eyes and nostrils. These are probably used for a second olfactory capability, in addition to the normal sense of smell based in the nose.

This is Caecilia thompsoni, the world's largest caecilian
World's largest caecilian, Caecilia thompsoni
Credit - Berkeley University

9# They breath with their lungs and skin
With the exception of two lungless species (Atretochoana eiselti and Caecilita iwokramae) all caecilians have lungs, but also use their skin or mouths for oxygen absorption. In most species, the left lung is much smaller than the right, an adaptation to body shape that is also found in snakes.

Submitted By You

1# Some species, like Typhlonectes natans, are born with large, sheet-like gills. These gills are lost shortly after birth.

References & Further Reading
- Nussbaum, Ronald A. (1998). Cogger, H.G. & Zweifel, R.G., ed. Encyclopedia of Reptiles and Amphibians. San Diego: Academic Press. pp. 52–59. ISBN 0-12-178560-2.
- Chisholm, Hugh, ed. (1911). "Caecilia". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- Mohun, S., Davies, W., Bowmaker, J., Pisani, D., Himstedt, W., Gower, D., Hunt, D., & Wilkinson, M. (2010). Identification and characterization of visual pigments in caecilians (Amphibia: Gymnophiona), an order of limbless vertebrates with rudimentary eyes Journal of Experimental Biology, 213 (20), 3586-3592 DOI: 10.1242/jeb.045914
- Kupfer, A., Müller, H., Antoniazzi, M., Jared, C., Greven, H., Nussbaum, R., & Wilkinson, M. (2006). Parental investment by skin feeding in a caecilian amphibian Nature, 440 (7086), 926-929 DOI: 10.1038/nature04403


  1. You missed a weird fact. The strange large external gills of newborn caecilians. http://youtu.be/1lAfOTR9tY4

  2. that's very cool! added to the post :)

  3. hehehehehe weird