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| Eastern newt | |
|---|---|
| aquatic adult stage | |
|
Conservation status
|
|
|
Least Concern (IUCN 3.1)[1] |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Caudata |
| Family: | Salamandridae |
| Genus: | Notophthalmus |
| Species: | N. viridescens |
| Binomial name | |
| Notophthalmus viridescens (Rafinesque, 1820) |
|
| Eastern newt range | |
The eastern newt (Notophthalmus viridescens) is a common newt of eastern North America. They frequent small lakes, ponds, and streams or near-by wet forests. They can coexist in an aquatic environment with small, noncarnivorous fish, as their skin secretes a poisonous substance when the newt is threatened or injured. They have lifespans of 12 to 15 years in the wild, and may grow to five inches in length. These newts are common aquarium pets, being either collected from the wild or purchased. The bright orange juvenile stage, which is land-dwelling, is often known as the red eft. Some sources blend the general name of the species and the red-spotted newt subspecies name into eastern red-spotted newt (although there is no "western" one).[2][3]
The eastern newt has these subspecies:[4]
Eastern newts have three stages of life: (1) the aquatic larva or tadpole, (2) the red eft or terrestrial juvenile stage, and (3) the aquatic adult.
The larva possesses gills and does not leave the pond environment where it was hatched. Larvae are brown-green in color, and shed their gills when they transform into the red eft.
The red eft is bright orangish-red in color, with darker red spots outlined in black. An eastern newt can have as many as 21 of these spots. The pattern of these spots differs among the subspecies. During this stage, the eft may travel far, acting as a dispersal stage from one pond to another, ensuring outcrossing in the population.
After two or three years, the eft finds a pond and transforms into the aquatic adult. The adult's skin is olive green, but retains the eft's characteristic black-rimmed red spots. It develops a larger, blade-like tail and characteristically slimy skin.
It is common for the peninsula newt (N. v. piaropicola) to be neotenic, with a larva transforming directly into a sexually mature aquatic adult, never losing its external gills. The red eft stage is in these cases skipped.
Eastern newts home using magnetic orientation. Their magnetoreception system seems to be a hybrid of polarity-based inclination and a sun-dependent compass. Shoreward-bound eastern newts will orient themselves quite differently under light with wavelengths around 400 nm than light with wavelengths around 600 nm, while homing newts will orient themselves the same way under both short and long wavelengths.[2] Ferromagnetic material, probably biogenic magnetite, is likely present in the eastern newt's body.[3]
Eastern newts are at home in both coniferous and deciduous forests. They need a moist environment with either a temporary or permanent body of water, and thrive best in a muddy environment. During the eft stage, they may travel far from their original location. Red efts may often be seen in a forest after a rainstorm. Adults prefer a muddy aquatic habitat, but will move to land during a dry spell. Eastern newts have some amount of toxins in their skin, which is brightly colored to act as a warning. Even then, only 2% of larvae make it to the eft stage. Some larvae have been found in the pitchers of the carnivorous plant Sarracenia purpurea.[5]
Eastern newts eat a variety of prey, such as insects, small molluscs and crustaceans, young amphibians, worms and frog eggs.
Terrestrial juvenile stage ("red eft")
Aquatic larval stage
Eft near Northfield, Massachusetts
Eft navigating over leaves
Eft on North Fork Mountain in eastern West Virginia
Eft seen along a trail in Harriman Park, New York
|access-date= requires |url= (help)| Wikimedia Commons has media related to Notophthalmus viridescens. |
| Wikispecies has information related to: Notophthalmus viridescens |
Brossman, Kelly H.; Carlson, Bradley E.; Stokes, Amber N.; Langkilde, Tracy (April 2014). "Eastern Newt (Notophthalmus viridescens) larvae alter morphological but not chemical defenses in response to predator cues". Canadian Journal of Zoology 92 (4): 279–283. doi:10.1139/cjz-2013-0244.
| リンク元 | 「ブチイモリ」 |
| 関連記事 | 「Notophthalmus」 |
ブチイモリ属、ノトフタルムス属、Notophthalmus属