Caecilian slithering along dirt ground
Some Endangered

Caecilian

  • Class: Amphibia (Amphibians)
  • Order: Gymnophiona
  • Families: 5
  • Genera: 26 known
  • Species: 124 known

ABOUT

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. Caecilians usually come in shades of gray, brown, black, orange, or yellow. Some species have tiny, fishlike scales within the rings.

At home in dirt or 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. So, their eyes are tiny in some species or hidden under the skin or skull in other species, making just gray bumps for eyes.

Some South American species 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. Scientists have found that an organ in their ear picks up vibrations from the ground to help them detect predators and prey. Caecilians also use their sensitive tentacles. These are between the nostrils and the eyes and help caecilians find food or their way around.

HABITAT AND DIET

Dark gray colored caecilian coiled into a circle on moist dirt
The ebony-skinned caecilian looks like a cross between an eel and an earthworm, but it is an amphibian, like frogs and salamanders.

They get around. Ranging from Central Africa, Southeast Asia, and southern Mexico to Argentina, these unusual creatures prefer loose soil and leaf litter in tropical forests or near rivers and streams. 

Sharp in the tooth. They may look soft on the outside, but inside a caecilian’s mouth are dozens of needle-sharp teeth. The teeth can 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.

FAMILY LIFE

Oh, baby! Like salamanders, caecilians produce young in two different ways, depending on the species. Some female caecilian species 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 as they feed on plankton. Through a series of changes, a single lung replaces their gills. Their skin becomes thicker, the annuli develop, and sensory tentacles appear. At this point, the newly developed adult moves to the land and goes underground.

Some species give birth to live young that are fully developed inside the mother before they are born.

Still a mystery to me! Imagine—there are over 120 species of these 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!

AT THE ZOO

Worming their way into our hearts. The San Diego Zoo received two ebony-skinned caecilians in 1993. They were the first of any caecilian species in our collection. We didn't know much about them, but keepers did some research and learned they seemed to like worms—a lot! They each ate about 20 worms each week. Yet we could not find a way to display them to our guests, as the animals live (and hide) in dirt. 

We currently do not have any caecilians in our collection.

CONSERVATION

Habitat loss threatens many caecilian species. And they are often confused with snakes in some areas and killed on the spot. The Basilan Island caecilian Ichthyophis glandulosus is endangered.

You can help us bring species back from the brink by supporting the San Diego Zoo Global Wildlife Conservancy. Together we can save and protect wildlife around the globe.

Save Wildlife. Help us keep this and other species from disappearing forever.

LIFE SPAN

Up to 13 years in zoos; unknown in the wild

YOUNG

Some species lay 30 to 60 eggs, others give birth to 2 to 25 live young

SIZE

Longest: Caecilia thompsoni nearly 5 feet ((2.4 meters) long

Shortest: Idiocranium russell is 3.5 inches (90 millimeters) long

Weight: Up to 2.2 pounds (1 kilogram) depending upon the species

FUN FACTS

Caecilians are the only amphibians to have tentacles.

They get their name from the Latin for blind or hidden, “caecus.” This is apt, as many caecilian species have no eyes and all live underground.

Some caecilian species are born with short, blunt teeth, used peel off the outer layer of the mother’s thick skin for food. This behavior is called dermatotrophy.

DISCOVER WILDLIFE

More Animals & Plants from San Diego Zoo and San Diego Zoo Safari Park