Amphibians: Caecilian

Range: Central Africa, Southeast Asia, southern Mexico to Argentina Habitat: loose soil and ground litter in tropical forests, or in rivers or streams

Legless amphibians

Caecilians (pronounced seh-SILL-yens) are tropical amphibians that look like large worms or slick snakes. They have no arms or legs, and sometimes it’s hard to tell which end is the head and which is the tail! Their shiny skin is ringed with skin folds called annuli, and they usually come in shades of gray, brown, black, orange, or yellow. Some species have tiny, fishlike scales within the rings.

Different types of young

Like salamanders, caecilians produce young in two different ways, depending on the species. Some female caecilians lay eggs in damp holes near water. When the larvae hatch they have gills and a short, finned tail to help them swim in the water, feeding on plankton. Through a series of changes the gills are replaced by a single lung, the skin becomes thicker, the annuli develop, and sensory tentacles appear. At this point the newly developed adult returns to the land and goes underground. Some species give birth to live young that are fully developed inside the mother before they are born.

At home in the dirt or
the water

Most caecilians are burrowers, living in a network of tunnels underground. A hard, thick, pointy skull helps these amphibians dig in soft dirt. Because of their underground lifestyle, caecilians have little need to see or hear. Therefore, their eyes are very tiny in some species, or hidden under the skin or skull in other species, making just tiny gray bumps for eyes. Some species in South America spend their lives in water instead of on land. Caecilians don’t have ear openings, so it is doubtful they can hear sounds the way we do. They rely on their sensitive tentacles, located between the nostrils and the eyes, to locate their prey and find their way around.

My, what sharp teeth you have!

They may look soft on the outside, but inside a caecilian’s mouth are dozens of needle-sharp teeth. The teeth are used to grab worms, termites, beetle pupae, mollusks, small snakes, frogs, lizards, and even other caecilians! All food is swallowed whole. Caecilians have toxic glands in their skin that sometimes protect them from being eaten by other animals.

Still a mystery

Imagine—over 120 species of animals, some as long as we are, that number in the millions on at least 4 continents, and almost no one knows they’re there, let alone ever sees one. That’s probably why almost nothing is known of caecilians’ habits and lifestyle. We still have much to learn about this unusual amphibian!