Amphibia is a class from the Chordata phylum.
The amphibians are tetrapods, a class of vertebrate animals with four limbs. They are non-amniotes, which means that their eggs are not surrounded by the several membranes, some impervious, which enable mammals, reptiles and birds to reproduce on land. Amphibians typically reproduce in fresh water and are not found in the sea, with the exception of one or two frogs that live in brackish water in mangrove swamps. Most amphibians lay eggs that have a gelatinous coating, which swells when it comes in contact with water. The larvae that hatch from the eggs are mostly quite unsimilar to the adult form.
|Most frogs are characterized by a short body, webbed digits (fingers or toes), protruding eyes, bifid tongue and the absence of a tail. Frogs are widely known as exceptional jumpers, and many of the anatomical characteristics of frogs, particularly their long, powerful legs, are adaptations to improve jumping performance. Due to their permeable skin, frogs are often semi-aquatic or inhabit humid areas, but move easily on land.'|
|Most salamanders have four toes on their front legs and five on their rear legs. Their moist skin usually makes them reliant on habitats in or near water, or under some protection (e.g., moist ground), often in a wetland. Some salamander species are fully aquatic throughout life, some take to the water intermittently, and some are entirely terrestrial as adults.|
|Caecilians completely lack limbs, making the smaller species resemble worms, while the larger species with lengths up to 1.5 m (4 ft 11 in) resemble snakes. The tail is short or absent, and the cloaca is near the end of the body.|