Approximately 55 extant species in 15 genera are recognized in this morphologically and behaviorally diverse family of salamanders. Geographic distribution is the largest of any salamander family, with four disjunct centers. Salamandrids occur primarily in Europe (throughout most of Europe, South into northern Africa and east into Asia), and Asia (especially India, Southern China, and mainland Southeast Asia). Two genera are endemic to North America.
The salamandrids are informally subdivided into two subgroups, the "true salamanders" (including the genera Chioglossa, Mertensiella, and Salamandra), and the newts (the remaining genera). The "true salamanders" tend to be smooth skinned, while the newts are unlike all other salamanders in having rough skin that is not slimy.
Most adult salamandrids are small, rarely exceeding 20 cm in length, and brightly colored. All salamandrids have toxic skin secretions (some produce tetrodotoxins), and many have bright warning coloration that is used in defensive displays. Newts are extremely poisonous at all stages of their life history. One character that appears to diagnose the family is the presence of a fronto-squamosal arch in most genera. Most species have well-developed lungs.
All salamandrids have courtship displays in which the male circles the female and rubs her, sometimes grasping her before depositing his spermatophore. Fertilization is internal, and no parental care has been reported. Salamandrid larvae are aquatic, except for a few viviparous species that give birth to fully metamorphosed young. Three life cycles found in salamandrids with aquatic larvae include metamorphosis into terrestrial adults (typical of "true salamanders"); metamorphosis into partially or wholly aquatic adults (typical of newts); and the triphasic life cycle of some Notophthalmus populations in which aquatic larvae move onto land as non-reproductive terrestrial efts, then return to the water after several years as aquatic adults. Facultative neoteny also occurs in some species of true salamanders. True salamanders live in burrows under logs or stones in moist woodlands and subalpine meadows, emerging only on mild, damp nights. Partially terrestrial adult newts returning to the water to breed often undergo a partial "reverse metamorphosis" back to the larval condition, growing fin-like extensions on their backs and tails. Some species show a strong tendency to return to the same aquatic breeding site year after year. Salamandrids eat small invertebrates and, in some cases, anuran tadpoles, which they detect with both vision and lateral line organs.
Salamandrids are members of the suborder Salamandroidea, the "advanced salamanders" that include all internally-fertilizing salamanders. Past analyses have placed the salamandrids sister to Ambystomatidae and Plethodontidae, together forming the group of most derived salamanders. Most current analyses suggest instead that the Salamandridae are sister to the group comprised of Ambystomatidae and Dicamptodontidae. No single feature uniquely characterizes all salamandrids, but the family is nonetheless believed to be a monophyletic group. At least two currently recognized salamandrid genera, Triturus and Mertensiella, are probably not monophyletic.
Fossil salamandrids are well represented in Cenozoic deposits in Europe, from the Eocene through the Pleistocene. An extinct genus is known from the Miocene in Asia, and the extant North American genera are known as fossils beginning in the Oligocene.
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Heather Heying (author).
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.