KRE Search

Frog

.
Frog (animal), small, tailless animal with a squat body and long, powerful hind legs adapted for jumping. Frogs have large, bulging eyes and moist skin. They typically live on land but spend part of their time in the water. Most frogs develop from small, fishlike larvae called tadpoles or pollywogs that live in water. This life divided between water and land is typical of amphibians, a group of related animals that includes toads, newts, and salamanders as well as frogs.

Frog Life Cycle
Most frogs have a life cycle with two distinct stages, typically living in water as young and on land as adults. Adult frogs lay large numbers of eggs in water or other moist places (A). The eggs hatch into small, fishlike larvae called tadpoles (B), which grow larger as they feed on algae and bits of plant material in the water (C). As it begins metamorphosis, or change into the adult body form, the tadpole grows hind limbs (D). After both pairs of limbs are complete and the animal has exchanged its gills for lungs, the young frog crawls out on land (E). The frog resorbs the rest of its tail and continues to grow until it reaches its adult body size (F).

Becoming a frog , the legless tadpoles that hatch from a floating mass of frog eggs are the animal’s fishlike larval stage. Part of a true metamorphosis, they have gills and a tail, both of which disappear as the tadpole feeds and grows. When limbs and air-breathing lungs develop, the young frog, now a miniature replica of its parents, emerges from water to land.

Scientific classification: Frogs are members of the order Anura in the class Amphibia. The bullfrog and the West African goliath frog are members of the family Ranidae and are classified as Rana catesbeiana and Conraua goliath, respectively. Poison dart frogs comprise several genera of the family Dendrobatidae. The African clawed frog belongs to the family Pipidae and is classified as Xenopus laevis. Marsupial frogs are members of the genus Gastrotheca in the family Hylidae. The extinct gastric brooding frog, Rheobatrachus silus, is classified in the family Myobatrachidae. Eleutherodactylus is a genus of frogs in the family Leptodactylidae. The family Bufonidae includes 380 species of toads, including the African toad, which is a member of the genus Nectophrynoides. Darwin’s frog is in the family Rhinodermatidae and is classified as Rhinoderma darwini.

Photos