Newt

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Newts
Smooth Newt (Triturus vulgaris)
Smooth Newt (Triturus vulgaris)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Lissamphibia
Order: Caudata/Urodela
Family: Salamandridae

Newts are small, usually bright-colored semiaquatic salamanders of North America, Europe and Asia, distinguished from other salamanders by the lack of rib or costal grooves along the sides of the body.

Contents

[edit] Characteristics

Newts have the ability to regenerate limbs, eyes, spinal cords, hearts, intestines, and upper and lower jaws. The cells at the site of the injury have the ability to de-differentiate, reproduce rapidly, and differentiate again to create a new limb or organ. One theory is that the de-differentiated cells are related to tumour cells since chemicals which produce tumours in other animals will produce additional limbs in newts.[1] Many newts produce toxins in their skin secretions as a defense mechanism against predators. Taricha newts of western North America are particularly toxic; the Rough-skinned Newt (Taricha granulosa) of the Pacific Northwest produces more than enough tetrodotoxin to kill an adult human foolish enough to swallow a newt. In order to cause harm, the toxins have to enter the body by being ingested or entering a break in the skin.

[edit] Handling newts

Theoretically it is safe to handle newts provided one thoroughly washes one's hands as newts secrete a toxin that is harmful if swallowed or if it comes into contact with mucous membranes. Newts also have the ability to carry the salmonella bacteria, although it's not likely, which causes food poisoning-like symptoms for several days.[citation needed]

[edit] Development

Alpine newt larva
Alpine newt larva

Newts can take several years to reach sexual maturity. Their main breeding season is between February and June. They hatch as tadpoles from eggs laid in ponds or slow-moving streams. In the case of triturus even brackish water is used, but most species are more picky. (see image on the right) Then they undergo metamorphosis, during which they commonly leave the water, only to return to the water to live out their adult lives. During the time right after metamorphosis, many North American Newt species go through a phase called the eft phase. In some cases their skin changes color, but efts always live their life on land, almost never seen in the water. Only when the eft reaches adulthood will it begin to live its life in a more aquatic fashion, and may rarely venture onto land. Many newts will live out their adulthood on land and only visit water to breed.

[edit] Distribution

The three common European genera are the crested newts (Triturus sp.), the European newts (Tylotriton sp.), the banded newts (Ommatotriton sp.), and some individuals such as the Spanish Ribbed Newt (Plurodeles waltl), the largest newt, and the Alpine newt (Mesotriton alpestris).

In North America, there are the Eastern newts (Notophthalmus sp.), of which the red-spotted newt (Notophthalmus viridescens) is the most abundant species, but it is limited to the area east of the Rocky Mountains. The three species of coastal, or Western newts are the red-bellied newt, the California Newt, and the rough-skinned newt, all of which belong to the genus Taricha, which is confined to the area west of the Rockies.

In Southeast Asia and Japan, species commonly encountered in the pet trade include the firebelly newts (Cynops sp.), the paddletail newts (Pachytriton sp.), the crocodile newts (Tylototriton sp.), and the warty newts (Paramesotriton sp.). In the Middle East there are the Middle Eastern newts (Neurergus sp.).[2]

[edit] Etymology

The oldest form of the name is eft, which is still used for newly metamorphosed juveniles, but according to the Oxford English Dictionary it changed for unknown reasons first to euft and then to ewt. For some time it remained as an ewt, but the "n" from the indefinite article (an) shifted to form a newt. See A, an for other examples.

[edit] Newts in popular culture

[edit] Notes

  1. ^ www.bioscience.utah.edu [1]; Acessed 1/24/07
  2. ^ livingunderworld.com [2]; Accessed 2/5/07

[edit] External references