An appreciation of the physiology and morphology of the Caecilians (Amphibia : Gymnophiona)

The Gymnophiona are the least well known amphibian order, an unfortunate si tuation because these animals can clarify many aspects of amphibian natural history, vertebrate evolution, and the physiology of viviparity and fossor ial life. Our aims are to assemble a number of topics about the current kno wledge of Caecilian physiology and morphology, and to integrate our own obs ervations on the morpho-physiology of a Brazilian species (Siphonops annula tus). We start with a brief discussion of the evolution of the group and so me general aspects of its ecology and behavior. Then we cover the external anatomy, emphasizing morpho-physiological aspects of skeleton, skull, teeth and integument. Then we cover ventilation and gas exchange, blood and circ ulation, and some aspects of water exchange and sensory organs, stress the fascinating aspects of physiology and morphology associated with viviparity , and finish with a brief discussion about Caecilian energetics. We hope th at this review will extend the interest in the group and become both a help ful reference and a source of insight for scientists in search of new quest ions. (C) 1999 Elsevier Science Inc. All rights reserved.