Family Ascaphidae - Tailed Frogs
Number of Species in the World and in Canada
There is only one species in this family, both worldwide and in Canada.
Tailed frog (Ascaphus truei)
Tailed frogs do not actually have a tail, but males possess a tail-like copulatory organ that enables these frogs to practice internal fertilization, unlike any other frog. Other unique characteristics include ribs that are not fused to the backbone and the presence of tiny tail wagging muscles, remnants of their evolution from tailed ancestors. They have vertical eye pupils, a characteristic shared by only one other family (Pelobatidae).
These frogs are restricted to fast flowing streams where they feed on terrestrial and aquatic insects. Because their tongues are attached to the back of their mouths, they can not flip it out of their mouths to catch flies like most other frogs. Instead, they prey on terrestrial and aquatic insects.
Tailed frogs are unique because they fertilize their eggs internally. During breeding season, males also develop black pads on the palms of their front feet, their arms, and their upper chest. The tadpoles have a sucker-like mouth disc to cling to the surface of rocks in a swift flowing stream.