Frogs don’t usually strike me as creatures that have tails, unless of course you’re talking about tadpoles. But there are two species of frogs that do have tail-like appendages. These are the aptly named tailed frogs. These unique frogs are quite amazing animals, as you will soon see.

Tailed frogs are found in the western United States as well as in British Columbia. They inhabit areas that contain cold, clear streams. These are usually in mountainous regions, though the frogs try and avoid areas that are too flat or too steep. Tailed frogs rely on streams to live, and require specific characteristics of the streams. The waters must not be too warm, even in the summer, and the frogs prefer areas that are forested. The trees help keep temperatures in the water consistent as well as preventing sedimentation in the stream.

A great picture of a male tailed frog, showing the extended cloaca.  Image source:
A great picture of a male tailed frog, showing the extended cloaca.
Image source:

To adapt to fast flowing stream environments tailed frogs have a number of interesting morphological traits. They have small lungs in comparison to other frogs, which helps to reduce the frogs’ natural buoyancy. Their feet are equipped with hardened toes that help the frogs grip the rocky steam bottoms. Tailed frogs also lack ear drums, as the constant sound of flowing water interferes with any attempt at acoustic communication.

Of course, one of the most obvious adaptations to living in fast flowing water are the frogs’ “tails”, which are actually only present in males. These tails are used for internal fertilization, a trait that is extremely rare among frogs and toads. The tails are actually extensions of the males’ cloacae, and are inserted into the female during reproduction. This prevents the males’ semen from being washed away by the turbulent water as it would be if the frogs used external fertilization.

Mating season occurs in the fall, usually between September and October. However, female tailed frogs store sperm internally and do not deposit eggs until the summer. They attach their eggs to the base of a rock where the eggs stay until they hatch, which usually takes about six weeks. The tadpoles of tailed frogs also have adaptations for living in streams; these include flattened bodies, and sucker-like mouths that can attach to boulders or rocks. Development into adult frogs can take anywhere from 1 to 4 years, and sexual maturity may not be reached until eight years of age.

A tadpole flipped upsidedown so the sucker mouth is visible. I think it's pretty creepy looking.  Image source: Wikipedia
A tadpole flipped upsidedown so the sucker mouth is visible. I think it’s pretty creepy looking.
Image source: Wikipedia

Turbulent streams are not very welcoming habitats, but the tailed frog seems to have figured out how to thrive in them. Though the frogs leave their streams at night to forage for food, they rarely stray far from their home waters, and their survival is dependent on such habitats. Luckily for us, such hostile environments often lead to interesting adaptations and the tailed frog is no exception.

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