Frog

Afrana

Characteristics

Frogs range in size from less than 50mm (2.0 in) to 300mm (11.8 in) 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.

Related Topics:
Goliath frog - Cameroon - Pupil

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The skin is smooth, unkeratinized and hangs loosely on the body because of the lack of loose connective tissue.

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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. 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.

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Croaking

Many species of frog (and toad) 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 (e.g. Rana temporaria in Britain and Rana pipiens (leopard frog) etc in the USA.) The croak of the American bullfrog Rana catesbiana is sometimes spelt "jug o' rum". The Ancient Greeks (for example Aristophanes) 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. Rigveda book 7 hymn 103 describes frogs with different calls (gomāyu = "having a voice like a cow's" and ajamāyu = "having a voice like a goat's") calling when the rains bring the breeding season.

Related Topics:
Bullfrog - Ancient Greeks - Aristophanes - Rigveda

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Poison

Some species of frog secrete toxins from their skin. These toxins deter predatory animals from eating them, and some are extremely poisonous to humans. Generally the frog obtains the poision from the insects or animals they eat. The Australian corroboree frogs pseudophryne corroboree and pseudophryne pengilleyi have very recently been discovered to be able to manufacture a unique alkaloid which is not derived from their diet (Daly). Some natives of the Amazon area extract poison from the poison dart frog and put it on their arrowheads when hunting.

Related Topics:
Toxin - Corroboree frog - Alkaloid - Amazon - Poison dart frog - Arrow

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