Rocky Mountain Tailed Frogs were only recently considered a distinct species from the Coastal Tailed Frog, so much of the information regarding morphology and ecology applies to both species. Rocky Mountain Tailed Frogs are very unusual looking frogs. They do not have an external eardrum (tympanum) and males have an external copulatory organ that looks like a tail. Rocky Mountain Tailed Frogs are small, growing to 4-5 cm body length, and, like most other frogs, males are generally smaller than females. They can also be recognized by their vertical pupil, bumpy skin, flattened and webbed hind toes, and lack of dorsolateral folds. Rocky Mountain Tailed Frogs are generally dark coloured and range from olive, grey, tan, brown, or black with adults having black speckling on the body and sometimes light and dark blotching on the back. They will sometimes have a dark-edged light bar or triangle between the eyes, and some will have a dark stripe on the face. The belly is cream coloured. Both tadpoles and adults are well adapted to living in fast-flowing streams. Tadpoles have a sucker-like mouth that they use to cling to rocks and debris in fast flowing water. The tadpole body is dorso-ventrally flattened with a low tail fin. They are dark grey or dark brown and usually have tan mottling, often with a white spot on the tail. Tadpoles grow up to 6 cm in body length before metamorphosis. Tailed Frogs are the longest living frogs in North America, reaching up to 20 years of age.