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Checklist of Amphibian Species and Identification Guide

Tailed Frog, Ascaphus truei


Tailed Frog Tailed Frog
The Tailed Frog, Ascaphus truei, is found in cold, fast-moving streams with boulders and stoney bottoms. They are unique in that they are the only species of frog with a tail. In reality it is a mating organ found only in males, and is an adaption to life in fast moving streams. In most frogs fertilization of eggs is external, the male "sprays" sperm on the eggs as they leave the female. In the fast moving streams that this species lives in this is not a viable mode of reproduction. However, in the tailed frog fertilization is internal and the female lays her fertilized eggs under stones where they are protected from the current. The tadpoles are able to hold fast to rocks and not be swept a way by the current with their mouths as the tadpole above is doing on a piece of glass. Tailed frogs reach up to 2 inches in length. They can be brown, gray or reddish in coloration with a light colored, somewhat triangular spot on the head in front just before the eyes.
Tailed Frog
In the photo above are a pair in amplexus, the mating position of frogs. Note that the male is holding the female just in front of the back legs (pelvically). In most frogs amplexus is pectoral, the male holds the female just behind the arms. In North America the only other frogs with pelvic amplexus are the Spadefoots (Pelobatidae).
Tailed Frog Range

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