One of the most ancient frog lineages on Earth — split off 100+ million years ago. The "tail" on males is actually a copulatory organ for internal fertilization (unique among frogs!), an adaptation for breeding in fast water.

Also called: Tailed Frog, Pacific Tailed Frog

Native status: Native to Pacific Northwest

§ Quick facts

SizeAdults 3.5–5 cm (1.4–2 in)
Weight2–6 g
LifespanWild 15–20 years
OrderAnura
FamilyAscaphidae

§ Encyclopedia

The tailed frogs are two species of frogs in the genus Ascaphus, the only taxon in the family Ascaphidae. The "tail" in the name is actually an extension of the male cloaca. The tail is one of two distinctive anatomical features adapting the species to life in fast-flowing streams. These are the only North American frog species that reproduce by internal fertilization. They are among the most primitive known families of frogs.

Source: Wikipedia — Tailed frog Licensed under CC BY-SA 4.0

§ Identification

Field marks. Small olive-gray frog with vertical pupils, granular skin, and (males only) a small posterior projection that looks like a tail.

Similar species. Rocky Mountain Tailed Frog (inland populations). No other US frogs have vertical pupils + tail extension.

Voice. Cannot vocalize — lacks vocal sac (an adaptation to noisy stream habitat where calls would be inaudible).

§ Diet & behavior

Diet. Adults: small invertebrates (springtails, mites, beetles). Tadpoles: diatoms and algae scraped from rocks with specialized suction-cup mouth.

Behavior. One of only two tailed frog species in the world (both North American). Males have a tail-like extension used for internal fertilization — a behavior unique among frogs. Tadpoles take 1–4 years to metamorphose. Restricted to cold (<15°C) fast-flowing forested streams.

§ Range

Coastal Pacific Northwest from Alaska to northern California

§ Habitat

Cold, fast-flowing mountain streams in old-growth forest

§ Threats

Logging-driven sediment in streams, road construction, climate-driven stream warming.

§ Conservation status

According to the IUCN Red List, the coastal tailed frog is currently classified as Least Concern.

§ What helps

Support old-growth forest protection. Maintain forested stream buffers (especially riparian shading). Reduce sediment runoff.

Support our work More ways to help

§ Further reading

§ Sources cited

  • AmphibiaWeb
  • USGS Forest and Rangeland Ecosystem Science Center
  • IUCN Red List 2014