ASIAN TAILED CAECILIANS: Ichthyophiidae

PHYSICAL CHARACTERISTICS

Asian tailed caecilians (sih-SILL-yuhns) are medium-sized to large caecilians that have a true tail. The mouth opens at the bottom of the head because the upper jaw is longer than the lower jaw. The jaw has a dual-action mechanism like a seesaw. The tentacle openings in Asian tailed caecilians are in front of the eyes, usually no more than halfway to the nostrils.

Caecilians look like earthworms. A series of rings runs the length of the body starting just behind the head. The rings are inside the body and attached to the vertebrae (VER-teh-bree), or the bones that make up the spinal column. Asian tailed caecilians have three rings per vertebra (VER-teh-bruh, the singular of vertebrae). Some species have as many as 420 rings. The skin is folded over the rings, making grooves between the rings. In Asian tailed caecilians the grooves go all the way around the body. The second and third sets of rings make shallower grooves than the main set. Asian tailed caecilians have a large number of scales under the skin in all the ring grooves.

Asian tailed caecilians are either solid purplish gray or purplish gray with paler stripes of the same color. Adult Asian tailed caecilians are 7 to 22 inches (18 to 56 centimeters) long from tip of snout to tip of tail.

GEOGRAPHIC RANGE

Asian tailed caecilians live in India, Sri Lanka, the Philippines, southern China, Thailand, Myanmar, Laos, Vietnam, Indonesia, and the Malay Archipelago west of Wallace's line.

HABITAT

Asian tailed caecilians live in leaf litter and soil in tropical rainforests. Many species do well, however, in areas that have been cleared of trees for farming.

DIET

Little is known about the feeding habits of Asian tailed caecilians. Scientists have opened up these animals and found large amounts of soil, which is evidence that an animal eats earthworms. The scientists also have found partially digested earthworms and pieces of insects inside caecilians. In captivity Asian tailed caecilians are fed earthworms, crickets, and even strips of beef, fish, and chicken.

BEHAVIOR AND REPRODUCTION

Asian tailed caecilians are burrowers. Newly hatched larvae are attracted to light. Larvae (LAR-vee) are animals in an early stage that change body form in a process called metamorphosis (MEH-tuh-MORE-feh-sis) before becoming adults. In captivity adults leave their burrows at night and crawl on the surface. In their natural habitats Asian tailed caecilians have been found on the surface at night during heavy rains.

At mating time, male Asian tailed caecilians place sperm directly inside a female's cloaca. The cloaca (kloh-AY-kuh) is the chamber in some animals that holds waste from the kidneys and intestines, holds eggs or sperm about to be released to the outside, holds sperm entering a female's body, and is the passage through which young are born. Fertilization (FUR-teh-lih-ZAY-shun), or the joining of egg and sperm to start development, takes place inside the female's body. The female then lays large white eggs strung together by jelly strands. The female takes care of the eggs in hidden nests until hatching.

Upon hatching, the larvae of Asian tailed caecilians leave the nest and wriggle to a stream, where they spend an unknown amount of time feeding on small water animals until they transform into young that look like small adults but are not yet able to reproduce. At this point, Asian tailed caecilians leave the stream and take up a land-based, burrowing lifestyle.

ASIAN TAILED CAECILIANS AND PEOPLE

Asian tailed caecilians have no known importance to people.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists two species of Asian tailed caecilians as Vulnerable, or facing high risk of extinction in the wild.

CEYLON CAECILIAN (Ichthyophis glutinosus): SPECIES ACCOUNT

Physical characteristics: Ceylon caecilians are medium-sized to large caecilians that reach a length of 9 to 16 inches (23 to 41 centimeters). Adults have 342 to 392 rings along the body. The tentacle openings are closer to the eyes than to the nostrils and are close to the sides of the mouth. These caecilians are purplish gray with yellowish cream stripes on the sides.

Geographic range: Ceylon caecilians live in Sri Lanka.

Habitat: Most Ceylon caecilians have been found in areas that were once rainforests but have been converted to farmland. These animals were found in piles of rotting plant matter and manure and in loose, wet soil. One caecilian was dug up from the soil of a moist meadow.

Diet: Newly transformed and adult Ceylon caecilians mainly eat earthworms but also eat other small invertebrates (in-VER-teh-bre-hts), or animals without backbones, that they find in the leaf litter and soil. Scientists do not know what the larvae eat in the wild, but in captivity they eat small bloodworms and earthworms.

Behavior and reproduction: When it grasps its earthworm prey, a Ceylon caecilian moves backward into its burrow while vigorously twisting its head and neck to subdue the worm. Sometimes the caecilian spins its body to break the earthworm into smaller, more manageable pieces.

Scientists know little about how Ceylon caecilians mate. The females lay twenty-five to thirty-eight large white eggs in jelly strings then place them in hidden nests in the soil. They then coil around the eggs until they hatch. The newly hatched larvae are 3 to 4.5 inches (8 to 11 centimeters) long. The larvae go through metamorphosis after about 280 days.

Ceylon caecilians and people: Ceylon caecilians have no known importance to people.

Conservation status: Ceylon caecilians are not considered threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Duellman, William E., and Linda Trueb. Biology of Amphibians. Baltimore, MD: Johns Hopkins University Press, 1994.

Lamar, William W. The World's Most Spectacular Reptiles and Amphibians. Tampa, FL: World, 1997.

Lawlor, Elizabeth P. Discover Nature in Water and Wetlands. Mechanicsburg, PA: Stackpole, 2000.

Llamas Ruiz, Andres. Reptiles and Amphibians: Birth and Growth. New York: Sterling, 1996.

Petranka, J. W. Salamanders of the United States and Canada. Washington, DC: Smithsonian Institution Press, 1998.

Web sites:

"Caecilian." Animal Bytes.http://www.sandiegozoo.org/animalbytes/t-caecilian.html (accessed on April 11, 2005).

Hawes, Alex. "On Waterdogs, Mudpuppies, and the Occasional Hellbender." Zoogoer.http://nationalzoo.si.edu/Publications/ZooGoer/2000/2/waterdogsmudpuppieshellbender.cfm (accessed on April 11, 2005).

Summers, Adam. "Squeeze Play." Natural History.http://biomechanics.bio.uci.edu/_html/nh_biomech/caecilian/caecilian.htm (accessed on April 11, 2005).