Frog Facts

Frogs are amphibians in the Order Anura, which includes true frogs and toads. The term "frog" is a popular name for animals that look like toads, but are generally more slender, have a less warty and dry skin, have long legs adapted for leaping and are more aquatic. It has no meaning in animal systematics, since many anuran families include both "frogs" and "toads". The true frogs are the Ranidae and the true toads are the Bufonidae.

Frogs range in size from less than 2.0 inches to 11.8 inches in Conraua goliath, the Goliath frog from Cameroon, which is the largest known frog. Frogs can have horizontal pupils, like tree frogs and true frogs, or vertical pupils, like the painted frogs. The skin is smooth, unkeratinized and hangs loosely on the body because of the lack of loose connective tissue.

Generally, frogs have long legs with webbed toes. The true frogs have a tongue with two lobes on its free end; it is attached in front. True frogs have three eyelid membranes: one transparent to protect the eyes underwater, and two which are translucent to opaque like human eyelids. They have a tympanum on each side of their head, which is involved in hearing.

Many species of true frogs and true toads have deep calls, or croaks. Frog noise tends to be spelt for English speakers as "crrrrk" in Britain and "ribbit" in the USA. This difference is due to Britain and the USA having different species of frogs. The croak of the American bullfrog is sometimes spelt "jug o' rum". The Ancient Greeks spelt the croak of the usual Greek species of frog as "korax" or "brekekekex co-ax co-ax": that species is probably Rana ridibunda. Small tropical frogs tend to have higher-pitched calls.

In many parts of the world the true frogs population has declined drastically over the last few decades. Many environmental scientists feel that amphibians, and true frogs in particular, may be excellent biological indicators of ecosystem function because of their place in the food web, their permeable skins, their typically bi-phasic life history (in both water and on land), and how diverse and dense they have historically been in many areas.

Although habitat loss is certainly one of the most important features of most declines, pollutants, climate change, parasitic infestation, introduction of non-indigenous predators/competitors, and infectious diseases have also been implicated.