Tail frogs

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Tail frogs
Western tail frog (Ascaphus truei)

Western tail frog ( Ascaphus truei )

Systematics
Superclass : Jaw mouths (Gnathostomata)
Row : Land vertebrates (Tetrapoda)
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Family : Ascaphidae
Genre : Tail frogs
Scientific name of the  family
Ascaphidae
Fejérváry , 1923
Scientific name of the  genus
Ascaphus
Stejneger , 1899

Tail frogs ( Ascaphus ) are a genus of frogs (Anura) consisting of only two species . They are among the primeval frogs of the Archaeobatrachia and occur in North America. The New Zealand primeval frogs (Leiopelmatidae) are considered to be their closest living relatives , with which they are also grouped into a family in some taxonomic overviews. Here the tail frogs are placed in their own family, Ascaphidae.

Features and way of life

Only the six species of the families Ascaphidae and Leiopelmatidae, which are treated as a separate suborder "Amphicoela" in older systematics, have nine free vertebrae; the remaining frogs have five to eight. The vertebrae are amphicoel, that is, shaped inward on both sides, and have cartilaginous intervertebral discs. Anatomically particularly noticeable is the presence of free ribs that are not fused with the transverse processes of the vertebrae, as is otherwise only the case with very few other frogs, for example the toad and the disc beater .

Externally, the tail frogs are quite small (up to about five centimeters long), inconspicuous brown colored amphibians. They live mainly aquatic in fast flowing, cold rivers, but occasionally go ashore in the surrounding forest areas. The name comes from the fact that the males have a three to ten millimeter long, tubular, evertable extension on their cloaca . They use these as mating organs and are the only frogs to have internal fertilization. The behavior is interpreted as an adaptation to the habitats in rapid river currents, where the external insemination of the spawn , which is otherwise common in anuras, would not be effective. The males do not have a mating call. The females keep the sperm received in early autumn until the following summer and only then deposit string-like clutches of 30 to 50 colorless eggs on the underside of large stones in the river bed. They are only ready to spawn every other year.

The tadpoles take an unusually long time to develop from one to four years to metamorphosis . They have a special suction mouth to hold on to objects in the current and not to be drifted away. Similar to a leech , they occasionally suck on the legs of bathers (but without drawing blood). The young do not become sexually mature until they are seven or eight years old.

Taxonomy

  • Family Ascaphidae Fejérváry, 1923
    • Genus Ascaphus Stejneger, 1899
      • Species Ascaphus montanus Mittleman & Myers, 1949 - Eastern or Rocky Mountains tail frog
      • Species Ascaphus truei Stejneger, 1899 - Western or coastal tail frog

distribution

Today's distribution of the genus Ascaphus in North America

The homeland of the tailed frogs is the northwestern United States and southwestern Canada . Specifically, they colonize the Canadian province of British Columbia and the US states of Washington , Oregon , California , Idaho and Montana , with the species Ascaphus truei inhabiting the Pacific coast region (including: Cascade Mountains ) up to the tree line , while Ascaphus montanus further east in occurs in the Rocky Mountains .

Danger

In recent years, the clear-cutting of surrounding forest areas has been identified as an indirect risk factor for the western tail frog: Due to the lack of shade from the trees, algae growth is increasing. The tadpoles can no longer securely attach themselves to the slimy surfaces of the stones in the river bed and drift away.

Both species are in the Red List of IUCN (not endangered at present than in its total inventory least concern classified).

swell

literature

  • Günther E. Freytag, Bernhard Grzimek, Oskar Kuhn, Erich Thenius (eds.): Lurche . In: Fish 2, amphibian. dtv, Munich 1980, ISBN 3-423-03204-9 ( Grzimeks Tierleben. Vol. 5; unchanged reprint of the Zurich edition 1975-77).

Web links

Commons : Tail Frogs  - Collection of images, videos and audio files