Tailed frog
Encyclopedia
The tailed frogs are two species of frog
s. The species are part of the genus, Ascaphus is the only taxon in the family Ascaphidae (icon). 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. It is the only North American frog that reproduces by internal fertilization
.
, the single species being the tailed frog (Ascaphus truei Stejneger
, 1899). However in that year Nielson, Lohman, and Sullivan published evidence in Evolution
that promoted the Rocky Mountain tailed frog (Ascaphus montanus) from a subspecies
to its own species. Since then, the former species has been formally called coastal tailed frog.
The existence of the visible "tail" appendage makes this frog family distinct from all other frogs. Thus its wider classification is difficult. It is usually classified in the Archaeobatrachia
suborder of ancient frogs, though some say it should be a sister to all other frogs. The "tail" is found only in males, and is actually part of the cloaca, used to insert sperm into the female during mating. This anatomical feature improves breeding success by minimizing loss of sperm in the turbulent, fast-flowing streams inhabited by this species. Thus, the tailed frogs exhibit internal fertilisation, rather than the external fertilisation found in other frogs.
These frogs are primitive in having a greater number of vertebrae than other frogs, in lacking the ability to vocalise
, and in possessing free ribs. They are small 2.5 centimetre (0.984251968503937 in) to 5 centimetres (2 in) and are found in steeply-flowing streams in Montana, Idaho, Washington, Oregon, and northern California in the northwest United States
and southeastern British Columbia
.
The tailed frogs share certain characteristics with the Leiopelma
, a genus of primitive frogs native to New Zealand
, with which they may be phylogenetic sister taxa. The prehistoric Vieraella
belongs to the tailed frog family.
lasts from May through September, and females deposit their eggs in strings under rocks in fast-moving streams. Larva
e take one to four years to metamorphose in the cool, fast-moving mountain streams.
Adult
s forage primarily terrestrially along stream banks but also occasionally feed underwater. A wide variety of food items taken, including both aquatic and terrestrial larval and adult insect
s, other arthropod
s (especially spider
s), and snail
s. Tadpole
s consume small quantities of filamentous green algae and desmid
s. Large quantities of conifer pollen
are consumed seasonally by tadpoles.
During the day, adults seek cover under submerged substrates in the stream, or occasionally under similar surface objects close to the stream. Individuals have also been found in crevices in spray-drenched cliff walls near waterfalls. During winter individuals are less active
, especially inland, and appear to retreat beneath large logs and boulders. Tadpole
s require cool streams with smooth-surfaced stones with a minimum diameter of 55 millimetres (2.2 in). Tadpoles probably spend most of their time attached to such substrates by a large oral sucker
. The large, sucker-like mouth parts of the tadpoles are a second distinctive feature of the species enabling survival in turbulent water unsuitable for other frogs. They prefer turbulent water to smooth, swiftly flowing water.
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s. The species are part of the genus, Ascaphus is the only taxon in the family Ascaphidae (icon). The "tail" in the name is actually an extension of the male cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
. The tail is one of two distinctive anatomical features adapting the species to life in fast-flowing streams. It is the only North American frog that reproduces by internal fertilization
Internal fertilization
In mammals, internal fertilization is done through copulation, which involves the insertion of the penis into the vagina. Some other higher vertebrate animals reproduce internally, but their fertilization is cloacal.The union of spermatozoa of the parent organism. At some point, the growing egg or...
.
Taxonomy
Until 2001, the genus was believed to be monotypicMonotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
, the single species being the tailed frog (Ascaphus truei Stejneger
Leonhard Hess Stejneger
Leonhard Hess Stejneger was a Norwegian-born American ornithologist, herpetologist and zoologist. Stejneger specialized in vertebrate natural history studies. He gained his greatest reputation with reptiles and amphibians....
, 1899). However in that year Nielson, Lohman, and Sullivan published evidence in Evolution
Evolution (journal)
Evolution, the International Journal of Organic Evolution, is a leading monthly scientific journal that publishes significant new results of empirical or theoretical investigations concerning facts, processes, mechanics, or concepts of evolutionary phenomena and events. Evolution is published by...
that promoted the Rocky Mountain tailed frog (Ascaphus montanus) from a subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
to its own species. Since then, the former species has been formally called coastal tailed frog.
General morphology
Archaeobatrachia
Archaeobatrachia is a suborder of Anura containing various primitive frogs and toads. As the name literally suggests, these are the most primitive frogs. Many of the species show certain physiological characteristics which are not present in other frogs and toads, thus giving rise to this group...
suborder of ancient frogs, though some say it should be a sister to all other frogs. The "tail" is found only in males, and is actually part of the cloaca, used to insert sperm into the female during mating. This anatomical feature improves breeding success by minimizing loss of sperm in the turbulent, fast-flowing streams inhabited by this species. Thus, the tailed frogs exhibit internal fertilisation, rather than the external fertilisation found in other frogs.
These frogs are primitive in having a greater number of vertebrae than other frogs, in lacking the ability to vocalise
Animal communication
Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, is sometimes called Zoosemiotics has played an important part in the...
, and in possessing free ribs. They are small 2.5 centimetre (0.984251968503937 in) to 5 centimetres (2 in) and are found in steeply-flowing streams in Montana, Idaho, Washington, Oregon, and northern California in the northwest United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and southeastern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
.
The tailed frogs share certain characteristics with the Leiopelma
Leiopelmatidae
Leiopelmatidae, or New Zealand and North American primitive frogs, is a family belonging to the suborder Archaeobatrachia. Their relatively primitive form indicates that they have an ancient lineage...
, a genus of primitive frogs native to New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, with which they may be phylogenetic sister taxa. The prehistoric Vieraella
Vieraella
Vieraella is an extinct genus of frog from the Jurassic period of Argentina, and the oldest true frog known.Despite living around 200 million years ago, Vieraella was anatomically very similar to modern frogs. For example, its hind legs were adapted for jumping, and the skull already possessed the...
belongs to the tailed frog family.
General habitat
The habitat of the Tailed Frog is cold, fast moving streams with cobblestone bottoms. Tailed frogs are mostly aquatic, but adults may emerge during cool, wet conditions to forage terrestrially. Breeding seasonBreeding season
The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...
lasts from May through September, and females deposit their eggs in strings under rocks in fast-moving streams. Larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e take one to four years to metamorphose in the cool, fast-moving mountain streams.
Adult
Adult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
s forage primarily terrestrially along stream banks but also occasionally feed underwater. A wide variety of food items taken, including both aquatic and terrestrial larval and adult insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s (especially spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s), and snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s. Tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s consume small quantities of filamentous green algae and desmid
Desmid
Desmids are an order of green algae, comprising around 40 genera and 5,000 to 6,000 species, found mostly but not exclusively in fresh water. Most are unicellular, and are divided into two compartments separated by a narrow bridge or isthmus...
s. Large quantities of conifer pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
are consumed seasonally by tadpoles.
During the day, adults seek cover under submerged substrates in the stream, or occasionally under similar surface objects close to the stream. Individuals have also been found in crevices in spray-drenched cliff walls near waterfalls. During winter individuals are less active
Active
Active may refer to:Human Activity* An active lifestyle, a lifestyle characterized by frequent or various social, intellectual, and physical activities* An "active" in a fraternity or sororityComputers and electronics...
, especially inland, and appear to retreat beneath large logs and boulders. Tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s require cool streams with smooth-surfaced stones with a minimum diameter of 55 millimetres (2.2 in). Tadpoles probably spend most of their time attached to such substrates by a large oral sucker
Suckermouth
In fishes, a suckermouth is a ventrally-oriented mouth adapted for grazing on algae and small organisms that grow on submerged objects....
. The large, sucker-like mouth parts of the tadpoles are a second distinctive feature of the species enabling survival in turbulent water unsuitable for other frogs. They prefer turbulent water to smooth, swiftly flowing water.