Caecilians: Gymnophiona

Caecilians are excellent burrowers in the ground or in leaves. They pump their tentacles in and out while they are moving in order to investigate their surroundings. Caecilians sometimes twist their bodies rapidly when subduing prey that they have grasped with their mouths. Scientists do not know how water-dwelling and partially water-dwelling caecilians behave because these animals live in dark, cloudy water and are hard to observe.

Some caecilians lay eggs that hatch into free-living larvae that have small gills and tail fins. 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. Gills are organs for obtaining oxygen from water. Scientists believe the eggs are laid in burrows or under grass or leaf litter on land. The female guards the eggs until the newly hatched larvae wriggle into nearby streams, where they live until metamorphosis. After metamorphosis the caecilians again become land dwellers. Other caecilians go through metamorphosis while inside the eggs, so they hatch with the body form of adults.

While inside the female, some species of caecilians have fetal (FEE-tehl) teeth that are different from adult teeth. The developing young use the teeth to chew a nutrient liquid made by the inner lining of the egg tubes inside the mother and to stimulate production of this liquid. The fetal teeth are shed at or near birth.