Introduction

The amphibians have sprung up from fish-like ancestor and then in turn given rise to reptiles. Thus, amphibians consequently hold a very important intermediate position. The term amphibia was coined by Linnaeus although he kept both, the amphibians as well as some reptiles in this particular class.

Classification and Characteristics

Later on, naturalists and taxonomists placed the amphibians particularly in this class, although the characteristics of the old amphibians and those of recent ones are little more different. The main characteristics of Amphibians are:

They may be aquatic, terrestrial or both; these are cold-blooded (polkilothermous) animals. Their body temperature is variable and most of them undergo hibernation during winter. Some undergo aestivation during summer; the shape of the body is variable, it may be depressed or cylindrical and divisible into head, neck, trunk and tail or into head and trunk. The skin is thin, moist, glandular and devoid of exoskeleton. There is a pair of nostrils, which open into the buccal cavity. They are provided with valves to exclude water. The teeth are alike (homodont), acrodont and polyphyodont.

Endoskeleton is largely bony or ossified. The skull possesses two occipital condyles for the attachment to the vertebral column. Eyes are provided with movable lids and tear glands to clean and protect them in air. The brain has smooth cerebral hemispheres and the cerebellum is poorly developed. Fertilization is generally external, sometimes internal. Eggs are isolecithal and are covered with a gelatinous covering. They are laid in water.

Additional Information

This encyclopaedic work in three volumes is designed to present entire vital information on Amphibia. Profusely illustrated in the light of latest researches, this work is a dependable reference for students, teachers, and researchers in the discipline.