AP BIOLOGY

Detailed explanation-1: -Amphibians are vertebrates (animals with backbones) which are able, when adult, to live both in water and on land. Unlike fish, they can breathe atmospheric oxygen through lungs, and they differ from reptiles in that they have soft, moist, usually scale-less skin, and have to breed in water.

Detailed explanation-2: -∙ Aquatic animals like fishes and frogs lay their eggs in water.

Detailed explanation-3: -Today amphibians are represented by frogs and toads (order Anura), newts and salamanders (order Caudata), and caecilians (order Gymnophiona).

Detailed explanation-4: -Reptiles have scales, and their skin is dry. Amphibians do not, and their skin is often moist with mucus, which keeps them from drying up.

Detailed explanation-5: -Amphibian eggs can be laid in the water (top) or on land in moist environments (bottom). All frogs and some salamanders in Pennsylvania lay their eggs in water. Salamanders that lay their eggs on land often guard them from predators, like this red-backed salamander.