Eastern newt

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Eastern newt
Red-spotted newt (aquatic adult stage)
Conservation status
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
Red-spotted newt (terrestrial juvenile stage, known as a "red eft")

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 strikingly colored (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).[1][2]

Sub-species

The eastern newt has these subspecies:[3]

  • Red-spotted newt (N. v. viridescens)
  • Broken-striped newt (N. v. dorsalis)
  • Central newt (N. v. louisianensis)
  • Peninsula newt (N. v. piaropicola)

Life stages

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.

Larva

Red-spotted newt (aquatic larval stage)

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.

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.

Adult

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 outlined red spots. It has a larger and wider 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.

Homing

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.[1] Ferromagnetic material, probably biogenic magnetite, is likely present in the eastern newt's body.[2]

Habitat and diet

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.[4]

Eastern newts eat a variety of prey, such as insects, small molluscs and crustaceans, young amphibians, worms and frog eggs.

Captive care

A small group (two or three) of adult eastern newts can be maintained in a 10-gallon aquarium partially filled with unchlorinated water and equipped with an air-operated filter. While oxygenation is not necessary for the newts to breathe, it allows the bacteria that decomposes their waste to flourish. This prevents dangerous buildups of ammonia and other anaerobically produced chemicals. The aquarium should be topped with a screen lid to prevent the newts from escaping and to provide proper ventilation. The newts will require an area to haul out of the water from time to time; this can be provided with a piece of driftwood, a "turtle dock" sold by pet stores, an "island" (a patch of soil or gravel with sphagnum moss and liverwort), or with terra cotta pots filled with aquarium gravel. If desired, pothos, java fern, java moss, or other semiaquatic plants can be placed in the pot to help absorb nitrogenous waste produced by the newts. Hiding places for the newts should be provided in the form of aquarium plants and/or clay pots on the bottom of the aquarium. Water temperatures in the aquarium should stay between 60 and 70°F (16 and 21°C) during the simulated summer. To simulate a winter to induce breeding or simply to recreate wild conditions more accurately, water temperatures should approach but not drop below 40°F (4°C). About 10-20% of the water in the newt aquarium should be replaced every week. The newts should be fed bloodworms, earthworms, redworms, daphnia, mosquito larvae (collected from unpolluted sources), brine shrimp, and commercial amphibian diets (although some may refuse these prepared foods). Feeding some type of live food is necessary, even if the newt happily accepts dry or prepared foods. Any uneaten food should be netted out to avoid fouling the water.

Gallery

  • Two adult eastern newts in captivity

  • Eft near Northfield, Massachusetts

  • Adult eastern newt near a New Hampshire pond

  • Eft navigating over leaves

  • Eft on North Fork Mountain in eastern West Virginia

  • Eft seen along a trail in Harriman Park, New York

References

  1. ↑ 1.0 1.1 Borland, S. Chris (1998), "Use of a Specialized Magnetoreception System for Homing by the eastern red-spotted newt Notophthalmus viridescens", Journal of Experimental Biology 188 (1): 275–291 
  2. ↑ 2.0 2.1 Brassart, J.Kirschvink, L., Phillips, J., and Borland S. (1999) "Ferromagnetic Material in the Eastern Red-spotted Newt Notophthalmus viridescens" Journal of Expirimental Biology 202(22):3155-3160
  3. ↑ Behler, John L.; King, F. Wayne; King, F. Wayne (1979). The Audubon Society Field Guide to North American Reptiles and Amphibians (Chanticleer Press ed.). New York: Knopf. p. 276. ISBN 0-394-50824-6. Retrieved 4 September 2012. 
  4. ↑ Butler, J., Atwater, D., and Ellison, A. (2005) Northeastern Naturalist 12(1):1-10
  • Hammerson (2004). Notophthalmus viridescens. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006. Database entry includes a range map and justification for why this species is of least concern

External links

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