Taricha rivularis

Taricha

The genus Taricha consists of three species and four subspecies of Western Newts (sometimes referred to as Pacific Newts). All newts are part of the family Salamandridae. The three species within this genus are the California Newt, the Rough-Skinned Newt, and the Red Bellied Newt, all of which are found on the west coast of the USA.

Species

Genus Taricha (Western Newts / Pacific Newts) - 3 species

Differentiating between species

The Rough-skinned Newt (T. granulosa) and the California Newt (T. torosa) share several characteristics. Both are light brown to black on the upper body and orange to yellow on the underbelly. They have "pebbly" skin that is not slimy and they may grow to a length of 8 inches, which is large for a salamander. However, there are a few characteristics to tell them apart. Rough-skinned Newts have small eyes with dark lower eyelids, while California Newts have large eyes and light lower eyelids. Also, rough-skinned newts' upper teeth form a V shape, while those of the California newt form a Y shape. However, this is difficult to ascertain on a living specimen.

The Red-bellied Newt (T. rivularis) is brown on the upper body with a red underbelly, has grainy skin, and grows to between 5.5 and 7.5 inches. It can be distinguished from other coastal newts, not only by its red belly, but also by the lack of yellow in its eyes. Breeding males develop smooth skin and a flattened tail.

Behavior

Taricha spp. eat a diet largely consisting of invertebrates such as Blood worms and mosquito larvae. Most predators associate bright colors with poison (called aposematism) and therefore, if attacked, the newt will take up a defensive position, showing off the bright underbelly. If the predator is not deterred by this display the newt will probably be its last meal. Newts of this genus are primarily nocturnal and may be either fully aquatic or semi-aquatic. None are fully terrestrial as they must enter the water to breed. Juvenile newts, which are known as "efts", are primarily terrestrial until they reach sexual maturity.

Toxicity

All species within the genus Taricha possess the biotoxin tetrodotoxin (TTX), one of the most potent toxins known to science. However, the degree of toxicity varies between species and between populations within a species. In general, the Rough-skinned Newt (T. granulosa) is the most toxic species. Rough-Skinned newts from populations in Northern Oregon are more toxic than those from California and Washington. Those on Vancouver Island, in British Columbia, possess little or no TTX. Taricha can be lethal to humans if ingested and at least one human fatality occurred in Oregon from eating a Rough-skinned Newt. Eastern newts of the genus Notophthalmus (=Diemictylus of earlier authors) also secrete TTX, but in lesser amounts. When handling Taricha the toxins should not be allowed to come in contact with unbroken skin or mucous membranes. Proper hand washing after handling should prevent any problems with infection from Salmonella (which newts are known to carry) or ingestion of TTX, however, some individuals are known to be allergic to skin contact with the toxin. Also, as amphibians' skin is very permeable, hand washing before handling will reduce the possibility of the newt absorbing bacteria or other contaminants from the handler..

These newts are, however, often kept as pets and with proper lighting, feeding and hygiene they will readily adapt to aquarium life.

References

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