BURIED-EYED CAECILIANS: Scolecomorphidae

PHYSICAL CHARACTERISTICS

Buried-eyed caecilians (sih-SILL-yuhns) are small to medium-sized caecilians. The mouth opens on the bottom of the head because the upper jaw is longer than the lower jaw. The holes for the tentacles are on the bottom of the snout toward the sides, below the nostrils and even with, or slightly in front of, the front edge of the mouth. Buried-eyed caecilians are usually dark purplish gray on the back and sides and cream colored on the belly. Adult buried-eyed caecilians are 6 to 18 inches (15 to 46 centimeters) long.

Buried-eyed caecilians have characteristics that set them apart from other caecilians: The eyes, which are undeveloped and can only distinguish light from dark, are attached to and move with the tentacles and may be exposed when the tentacles are extended. Otherwise, they are covered with, or buried under, bone. Another distinguishing characteristic is that buried-eyed caecilians have no sound-conducting bones in their middle ears.

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. Some species of buried-eyed caecilians have one ring, and some have two rings per vertebra (VER-teh-bruh, the singular of vertebrae). The skin is folded over the rings, making grooves between the rings. Some species of buried-eyed caecilians have a small number of scales, and some have no scales, under their skin folds.

Buried-eyed caecilians have no tail. Instead, they have a thick shield of skin at the end of their body. This shield is bluntly rounded and flattened on the bottom side. The opening of the cloaca lies in a shallow, oval space. 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. The males of some species have hard spines on the penis.

In some species of buried-eyed caecilians the females are longer than the males because they have many more vertebrae and rings than the males. This characteristic may help the females because the body provides more space for developing young. Male buried-eyed caecilians have larger heads than females. Scientists believe this feature may help males fight one another for mates and territory.

GEOGRAPHIC RANGE

Buried-eyed caecilians live in Cameroon in the west of Africa and Malawi and Tanzania in the east of Africa. No caecilians of any kind have been found in central Africa. This distribution pattern is odd, because the vast region of the upper Congo seems ideally suited for caecilians. Caecilians probably live in central Africa but just have not been found.

HABITAT

Buried-eyed caecilians live in tropical rainforests and areas that have been cleared of trees, usually in hilly or mountainous regions. These animals usually are found in moist areas under logs and in leaf litter on the forest floor. They sometimes are dug up from moist soil. In Tanzania and Malawi, buried-eyed caecilians have been found in turned soil and in piles of old plant matter on farms.

DIET

Scientists believe buried-eyed caecilians eat earthworms and insects. In captivity they eat earthworms and small crickets.

BEHAVIOR AND REPRODUCTION

Buried-eyed caecilians are excellent burrowers. They pump their tentacles in and out when they are moving and otherwise investigating their surroundings. Their tentacles are thought to be sense organs for "tasting" their immediate surroundings. Because they have found bite marks on male caecilians in captivity and in nature, scientists believe the males fight one another for mates and for territory.

Some buried-eyed caecilians give birth to live young. After mating, the female keeps the fertilized (FUR-teh-lyzed) eggs, or those that have joined with sperm, inside her in egg tubes. Scientists believe the egg tubes make a nutritious liquid that the developing young eat with special teeth that are lost after they are born. These teeth are comblike, and they also may be used to stimulate the egg tube to secrete the "milk" near the mouth of the feeding young. Scientists believe the species of buried-eyed caecilians that do not give birth to fully developed young are egg layers. The young develop inside the eggs but have the adult body form when they hatch. Scientists believe the female takes care of the eggs until they hatch.

BURIED-EYED CAECILIANS AND PEOPLE

Buried-eyed caecilians have no known importance to people.

CONSERVATION STATUS

Buried-eyed caecilians are not considered threatened or endangered.

KIRK'S CAECILIAN (Scolecomorphus kirkii): SPECIES ACCOUNT

Physical characteristics: Kirk's caecilians reach a length of 8.5 to 18 inches (22 to 46 centimeters). They have 130 to 152 rings. The purplish gray color on the back extends down the sides of the animal almost to the center of the belly. The rest of the belly is cream colored. The top and sides of the head are dark like the rest of the upper part of the body, but there is a lighter area along the tentacle. The black retina of the eye at the base of the tentacle is visible through the skin and skull bones.

Geographic range: Kirk's caecilians live in Malawi and Tanzania.

Habitat: Kirk's caecilians live in tropical rainforests and farming areas, usually in mountainous regions. They live under and in surface leaf litter and in the soil.

Diet: Kirk's caecilians probably eat earthworms and insects.

Behavior and reproduction: Kirk's caecilians are efficient burrowers. They stick out their tentacles to investigate their surroundings. They also can make their eyes stick out beyond their skull bones. Scientists do not know how Kirk's caecilians mate. They do know that these caecilians give birth to young that have the body form of adults.

Kirk's caecilians and people: Kirk's caecilians have no known importance to people.

Conservation status: Kirk's 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).