Amphibians (class Amphibia) are a taxon of animals that include all tetrapods (four-legged vertebrates) that do not have amniotic eggs. Amphibians (from Greek αμφις "both" and βιος "life") generally spend part of their time on land, but they do not have the adaptations to an entirely terrestrial existence found in most other modern tetrapods (amniotes). more...
There are about 5,700 living species of amphibians. The study of amphibians and reptiles is known as herpetology. The fear of amphibians and reptiles is known as herpetophobia.
History of amphibians
Amphibians developed with the characteristics of pharyngeal slits/gills, a dorsal nerve cord, a notochord, and a post-anal tail at different stages of their life. They have persisted since the dawn of tetrapods 390 million years ago in the Devonian period, when they were the first four-legged animals to develop lungs. During the following Carboniferous period they also developed the ability to walk on land to avoid aquatic competition and predation while allowing them to travel from water source to water source. As a group they maintained the status of the dominant animal for nearly 75 million years. Throughout their history they have ranged in size from the 3 foot long Devonian Ichthyostega, to the slightly larger 5 foot long Permian Eryops, and down to the tiny Brachycephalus didactylus (Brazilian Gold Frog) and Eleutherodactylus iberia from Cuba, with a total length of 9.6-9.8 millimeters. Amphibians have mastered almost every climate on earth from the hottest deserts to the frozen arctic, and have adapted to climatic change with ease.
- Solomon Berg Martin, Biology
- Duellman/Trueb, Biology of Amphibians
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