Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods, excluding the amniotes. All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems. Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Salamander diversity is highest in eastern North America, especially in the Appalachian Mountains; most species are found in the Holarctic realm, with some species present in the Neotropical realm.
Amphiuma is a genus of aquatic salamanders from the United States, the only extant genus within the family Amphiumidae. They are colloquially known as amphiumas. They are also known to fishermen as "conger eels" or "Congo snakes", which are zoologically incorrect designations or misnomers, since amphiumas are actually salamanders, and not fish, nor reptiles and are not from Congo. Amphiuma exhibits one of the largest complements of DNA in the living world, around 25 times more than a human.
The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include some of the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two living families—the other being the Asiatic salamanders belonging to the family Hynobiidae—within the Cryptobranchoidea, one of two main divisions of living salamanders.
Plethodontidae, or lungless salamanders, are a family of salamanders. With over 500 species, lungless salamanders are by far the largest family of salamanders in terms of their diversity. Most species are native to the Western Hemisphere, from British Columbia to Brazil. Only two extant genera occur in the Eastern Hemisphere: Speleomantes and Karsenia.
Ambystomatidae is a family of salamanders belonging to the Suborder Salamandroidea in the class Amphibia. It contains two genera, Ambystoma and Dicamptodon. Ambystoma contains 32 species and are distributed widely across North America, while Dicamptodon contains four species restricted to the Pacific Northwest. These salamanders are mostly terrestrial and eat invertebrates, although some species are known to eat smaller salamanders. They can be found throughout the US and some areas of Canada in damp forests or plains. This family contains some of the largest terrestrial salamanders in the world, the tiger salamander and the coastal giant salamander. Some species are toxic and can secrete poison from their bodies as protection against predators or infraspecific competition. Neoteny has been observed in several species in Ambystomatidae, and some of them like the axolotl live all of their lives under water in their larval stage.
Sirenidae, the sirens, are a family of neotenic aquatic salamanders. Family members have very small fore limbs and lack hind limbs altogether. In one species, the skeleton in their fore limbs is made of only cartilage. In contrast to most other salamanders, they have external gills bunched together on the neck in both larval and adult states. Sirens are found only in the Southeastern United States and northern Mexico.
The spermatheca, also called receptaculum seminis, is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, oligochaeta worms and certain other invertebrates and vertebrates. Its purpose is to receive and store sperm from the male or, in the case of hermaphrodites, the male component of the body. Spermathecae can sometimes be the site of fertilisation when the oocytes are sufficiently developed.
Batrachoseps is a genus of lungless salamanders (plethodontids) often called slender salamanders. They can be distinguished from other lungless salamanders by the four toes they have on each foot.
The Western Cascades or Old Cascades are a sub-province of the Cascade Range in the U.S. state of Oregon, between the Willamette Valley and the High Cascades. The Western Cascades contain many extinct shield volcanoes, cinder cones and lava flows, and the region is highly eroded and heavily forested. Deposits of the same age as the Western Cascades are also found in southwest Washington state.
Ranodon is a monotypic genus of salamanders in the family Hynobiidae. It currently contains only one species, the Central Asian salamander. The species lives in streams and has reduced lungs. It was previously assumed the fertilization was the opposite of that other salamanders with external fertilization, with the male first depositing a large mass of sperm, which the female then placed her eggs on. But this appears to have been an error, and that the male fertilize the eggs only after the female has laid them.
The Cascade torrent salamander is a species of salamander in the family Rhyacotritonidae. It is endemic to the Pacific Northwest in the United States where it is found from Skamania County in Washington south to Lane County in Oregon on the west slope of the Cascade Mountains.
The Olympic torrent salamander is a species of salamander in the family Rhyacotritonidae. This is a small salamander that lives in clear, cold, mountain streams. It is medium to dark brown and may have a few small light spots on the sides and small dark spots on the tail; it is bright yellow on the belly, usually with some dark spots. Torrent salamanders typically have short snouts and relatively large eyes. As in other torrent salamanders, adult males have square-edged lobes behind the cloaca. These salamanders live at the edges of clear, cold, mountain streams; they can be abundant under gravel at stream edges and in the spray zones of waterfalls. During rainy seasons, they are occasionally found under objects on land away from streams.
The southern torrent salamander is a member of the salamander family Rhyacotritonidae. This species of torrent salamander is found the farthest south in the Pacific Northwest region. It is a small salamander endemic to the region from Northern California to Northern Oregon. It is one of four species of Rhyacotriton, along with R. cascadae, R. kezeri and R. olympicus. All species of Rhyacotriton are small, with their body lengths being less than 5 inches. The species reproduces annually, with an extended courtship and egg-laying period. The time it takes from oviposition to reach sexual maturity ranges from five to eight years, making the generation interval rather long. The larval stage, from hatching to metamorphosis, lasts 2.0-2.5 yr, with females requiring another 1.5–2.0 yr until they can first breed. They reach sexual maturity 1.0-1.5 yr after metamorphosis which occurs between 4.5 and 5.0 yr. This species feeds on small insects and spiders. Although it is found over a large area, it is not a migratory creature. It is preyed on by Pacific giant salamanders and garter snakes.
