Frogs on Phonecards

Frog, common name for an amphibian of the order that also includes toads. Frogs are native to all parts of the world, except Antarctica, but the greatest variety are found in tropical areas. Toads differ from frogs superficially in that toads generally have drier skin, often covered with "warts", and the majority spend most of their life on land.

Frogs are small animals with smooth, moist skin, bulging eyes that can see in almost any direction, and external eardrums behind the eyes, but lacking a tail in adults. Most species have long hind legs that enable them to take long leaps, and webbed feet, making them excellent swimmers.
The frog's internal systems are typical of most amphibians. In fact, amphibians were originally known as batrachians, from the Greek word for frog, batrachus.
Most frogs, especially males, are quite vocal. As the frog forces air from the lungs, vocal cords in the voice-box, or larynx, vibrate to make calls distinctive of its species. A much louder sound is produced by the males of species that possess a vocal sac, which swells enormously when the frog calls to attract a mate. The frog's tongue is attached at the front of the mouth instead of at the rear, and is covered with a sticky substance, making it an efficient trap for insects.
As a frog grows, it goes through a true metamorphosis, starting with an egg, then a fish-like larval stage, and ending with the adult frog stage. Frogs lay their eggs in water, where they hatch into tadpoles (short-bodied larvae) during early spring or summer. At this stage they have gills and a tail. The tadpole feeds on algae and other vegetation. As it matures, the tail is absorbed, lungs develop, the gills disappear, legs appear, and the adult frog emerges on to land.

One large and nearly worldwide family comprises the true frogs, many species of which are familiar. Two well-known true frogs of Europe are the common European frog and the edible frog, a popular food in parts of Europe. The common frog is about 8 cm (3 in) long and smooth-skinned, with markings that vary from brown, greenish, grey, or yellowish, and spots of black or reddish-brown. The bullfrog is the largest true frog in North America, and the leopard frog is one of the most common North American species. Most true frogs stay close to ponds and streams. The African giant frog is the largest of all true frogs: it grows as long as 66 cm (26 in) and weighs as much as 4.5 kg (10 lb).

Frog and Toad
Although toads and frogs are both amphibians, there are several basic anatomical differences between them. The smooth, moist skin characteristic of frogs covers long legs specialized for jumping and swimming. The skin of toads such as the green toad is dry and covered by knobby glandular projections often referred to as "warts". Toads have fairly stout, compact bodies. With relatively short legs, they lack the jumping ability and range of frogs. Toads are generally terrestrial and for the most part nocturnal.

True frogs make up the family Ranidae. The common European frog is classified as Rana temporaria, the edible frog as Rana esculenta, the leopard frog as Rana pipiens, and the African giant frog as Giantorana goliath. The hairy frog is classified as Astylosternus robustus. Bullfrogs are true frogs and belong to the family Ranidae.

frogs
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