Zweifel, Richard G. Department of Herpetology, American Museum of Natural History, New York, New York.
Cash, W. Ben Department of Biology, Maryville College, Maryville, Tennessee.
Last reviewed:November 2015
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The smallest order of the class Amphibia, consisting of the wormlike caecilians. The order Apoda is sometimes called Gymnophiona. Its members are known commonly as caecilians, which are wormlike, legless amphibians with indistinct or even hidden eyes. A series of annular grooves (annuli) are usually present along the length of the body, heightening the resemblance to an earthworm (see illustration). Most caecilians lead a burrowing existence, although members of one genus, Typhlonectes, are aquatic. Some species have the eyes hidden beneath the bones of the skull and probably are blind, but others at least are able to distinguish movement. A unique feature of some caecilians among modern amphibians is the presence of scales buried in the skin. See also: Amphibia; Burrowing animals; Lissamphibia; Scale (zoology)
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