Head to head
Rocky Mountain Tailed Frog vs Tailed Frog
A Rocky Mountain tailed frog and a tailed frog are extremely close relatives sharing one of the most unusual reproductive adaptations of any North American amphibian, separated mainly by which mountain range they call home.
| Rocky Mountain Tailed Frog | Tailed Frog | |
|---|---|---|
| Scientific name | Ascaphus montanus | Ascaphus truei |
| Range | Northern Rocky Mountains | Pacific coastal mountains, N. California to BC |
| Internal fertilization | Yes | Yes |
| Tadpole mouth | Sucker-like, grips rocks | Sucker-like, grips rocks |
| Tadpole development time | Several years | 1 to 4 years |
| Age at sexual maturity | Not specifically documented | 7 to 8 years |
| Adult lifespan | Not specifically documented | 15 to 20 years |
| Conservation status | Least Concern | Least Concern |
Rocky Mountain Tailed Frog vs Tailed Frog: common questions
How are the Rocky Mountain tailed frog and the tailed frog different?
The two were split into separate species mainly on genetic grounds tied to their different ranges, with the tailed frog occupying the Pacific coastal mountains from northern California to British Columbia and the Rocky Mountain tailed frog instead found across the inland northern Rocky Mountains, though both look and behave almost identically otherwise.
Why do both of these frogs fertilize their eggs internally?
Both species live in fast, cold mountain streams where releasing eggs and sperm externally into open water, as most frogs do, would risk the sperm being swept away by the current before fertilization could occur, making internal fertilization a shared adaptation to a shared type of demanding stream habitat.
Why do the tadpoles of both species have such an unusual mouth?
Both develop a large, disc-shaped sucker mouth that clamps onto submerged rocks, letting the tadpole hold its position in a current strong enough to sweep a person off their feet, releasing its grip only briefly to graze on algae before reattaching.