Eastern newt (Notophthalmus viridescens)

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Terrestrial red eft form of eastern newt
IUCN Red List species status – Least Concern LEAST
CONCERN

Top facts

  • The eastern newt is the second most widely distributed salamander species in the United States.
  • While the larvae and adults of the eastern newt are aquatic, the juvenile stage, known as an ‘eft’, is terrestrial.
  • The eastern newt carries out a special defensive posture known as the ‘unken reflex’, which involves the newt exposing its bright belly by bending its head and tail backwards so that they almost meet.
  • A carnivorous species, the eastern newt preys on a variety of species, including worms, snails and beetle larvae.
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Eastern newt fact file

Eastern newt description

KingdomAnimalia
PhylumChordata
ClassAmphibia
OrderCaudata
FamilySalamandridae
GenusNotophthalmus (1)

The eastern newt (Notophthalmus viridescens) is a small salamander with dry, granular, rather toad-like skin. It can be distinguished from many other similar species by the presence of raised crests between the eyes (4) and by the lack of obvious grooves running from under the front limbs to the groin (2) (3) (4).

The fully transformed adult eastern newt is olive green to yellowish-brown on the upperparts (2) (4) (5) (6), with small dark spots scattered all over its body (4) (5) (6). Red spots with black borders usually line the sides or back of this species (2) (3) (5) (7), and the largest of these spots tend to form a distinct row on each side of the body (2). The belly is yellowish in colour (2) (5), ranging from a duller straw colour to a brighter lemon-yellow, and is patterned with many black spots (2).

However, there is some variation in colour and pattern among the various subspecies of the eastern newt, with the central newt (Notophthalmus viridescens louisianensis) typically lacking the red spots, or sporting smaller spots with faded or incomplete black borders (2) (3). The broken-striped newt (Notophthalmus viridescens dorsalis) has a red stripe with a discontinuous black border running along its back (8). Male eastern newts in breeding condition have large hind legs (2) (4) with rough, black patches of skin on the inside of the thighs and on the tips of their toes (2) (4) (6).

Eastern newt larvae have relatively smooth skin, and are adorned with bushy gills and a rather conspicuous dark stripe which runs from the snout through each eye to the gills (2). The terrestrial juveniles of the eastern newt, known as ‘efts’, have rough, granular skin (2) (4) (6), and are typically red or orange in colour (4) (5) (6) (7) (9) with spots similar to those of the adult (2) (6). The belly of the eastern newt eft is yellowish or reddish (4).

Four subspecies of the eastern newt are currently recognised (2) (9).

Also known as
broken-striped newt, central newt, Peninsula newt, red spotted newt.
Size
Body length: 2.9 - 5.1 cm (2)
Total length: 5.8 - 14 cm (2)
Larvae length: 0.7 - 0.9 cm (2) (3)
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Eastern newt biology

The eastern newt is reported to have the most variable life history of all North American amphibians (9), with most populations having four main life stages: egg, larvae, eft and adult (2) (3) (4) (7) (9). While the adults and larvae are aquatic, the intermediate eft stage is typically terrestrial (2) (3) (4) (9). Efts are both diurnal and nocturnal, and are known to be more active on rainy days or nights when the ground is moist (9).

The eastern newt is carnivorous at all stages of its life (9). Feeding at night (9), the larvae of this species feed on whatever is most accessible (3), including snails, beetle larvae, clams, mites and crustaceans (2) (3) (9). Eastern newt larvae have also been reported to occasionally eat algae (3). Adult eastern newts use vision and chemical cues to locate prey that can be swallowed whole (9), and eat small aquatic invertebrates (3) such as molluscs, crustaceans, mayflies, worms and leeches (2) (3) (7) (9). In addition, the eastern newt feeds on the eggs and larvae of other amphibians (2) (3) (7) (9), as well as small fish and fish eggs (9). Eastern newt efts also feed on a variety of invertebrates (2) (3).

As a means of avoiding predation, the eastern newt produces toxic secretions from special glands in its skin (2) (3) (6). This toxin is present during all life stages (3), but efts tend to be more toxic than adults (2). Interestingly, the eastern newt carries out a rather spectacular warning display known as the ‘unken reflex’, which involves the amphibian closing its eyes and retracting them inwards before bowing its head and tail upwards so that they almost meet. In this posture, the brightly coloured belly is exposed (3) (9), which warns potential predators of its toxicity (2) (3) (9). Turtles, snakes and large frogs tend to be the main predators of adult eastern newts (2) (3), while raccoons and certain hawk species are known to avoid them (3).

Reproduction in the eastern newt is aquatic (9). The timing of breeding in this species varies with location, usually occurring during the winter and spring (2). The male eastern newt approaches a female and performs a short display which involves undulating his body and tail. If the female is receptive, it will nudge the male’s tail with its snout. This encourages the male to deposit a spermatophore, which the female then picks up with her vent (3). If the female is unresponsive, the male may grab her in amplexus, and fan its tail to waft secretions through the water toward the female (2). This may last several hours before the male dismounts and deposits a spermatophore for the female to pick up (2).

Egg laying in the eastern newt occurs in the spring in many parts of the species’ range (3) (4) (9), but may start in early winter in more southerly populations and carry on into July in northern populations (9). The female eastern newt deposits each egg individually (2) (3) (9), and lays several eggs per day (2) (9) over a period of a few weeks (3) (9), laying between 200 and 375 eggs in total (9). Each egg measures about 1.5 millimetres in diameter (9), and is attached to aquatic plants or other submerged vegetation (1) (2) (3) (4). The eggs incubate for a period of between three and five weeks (2) (3) (9) depending on the water temperature (3), after which time the larvae hatch out (2) (3) (9).

The length of the larval stage of the eastern newt varies across this species’ range, but usually lasts between two and five months, after which time it transforms into an eft (9). Efts migrate away from aquatic habitats to live in forested areas (9), and may spend up to seven years in this stage, although in some areas transformation occurs within two years (2). Efts then migrate from their terrestrial habitats back to aquatic habitats where they become sexually mature and breed (4) (9).

In some populations, there is no eft stage, and the larvae develop directly into adults. These individuals are known as neotenic adults (5) (9). Most eastern newts are thought to live for between 3 and 8 years, although they may live for up to 15 years (9).

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Eastern newt range

The eastern newt is the second most widely distributed salamander in the United States (9), and can be found throughout the eastern parts of the country (1), as well as in southern Canada (1) (3). The range of this species expands westwards to Minnesota, eastern Kansas and eastern Texas (1) (9), and southwards through Florida (3).  

The different subspecies of eastern newt have different geographical distributions. For instance, broken-striped newts (Notophthalmus viridescens dorsalis) occur in south-eastern North Carolina and north-eastern South Carolina (9), while the Peninsula newt (Notophthalmus viridescens piaropicola) is only found in peninsular Florida (8) (9). Central newts (Notophthalmus viridescens louisianensis) have a rather disjointed distribution, and the red-spotted newt (Notophthalmus viridescens viridescens) has the largest distribution of the four subspecies (9).

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Eastern newt habitat

Adult eastern newts and their larvae inhabit a variety of standing freshwater habitats, and can be found in ponds, canals, swamps and quiet stream pools (1) (2) (3) (7) (8) (9) with a muddy substrate (6). This species also occurs in the shallow regions of larger lakes (3), and larvae occur in water less than 0.5 metres deep, seeking cover under bottom debris during the day (9). Eastern newt habitat is usually located in or near forest (4), in open, sunny areas (9), and preferred sites generally contain a significant amount of aquatic vegetation (2) (3) (9).

Eastern newt efts are typically found in moist, wooded areas (1) (3) (5) (6) (7) (9), often taking shelter under rocks, leaf litter and rotting logs (3) (9).

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Eastern newt status

The eastern newt is classified as Least Concern (LC) on the IUCN Red List (1).

IUCN Red List species status – Least Concern

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Eastern newt threats

The eastern newt is widespread and abundant, and is not currently considered to be threatened with extinction. However, this species is thought to be negatively affected by roads which may serve as partial barriers to movement. The introduction of the bluegill sunfish (Lepomis macrochirus) may also cause declines in this amphibian, as it predates the eastern newt larvae (1).

In addition, in certain parts of its range, such as central and northern Illinois, the eastern newt population has declined as a result of deforestation and draining of ponds and marshes (4). Climate change, particularly in areas where drought conditions may persist, could also negatively affect the eastern newt in the future (9).

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Eastern newt conservation

The eastern newt is not currently believed to be in need of protection (1), and there are no known conservation measures in place for this species at present. However, the eastern newt does occur in many protected areas (1), and it is thought that the creation of small ponds containing lots of vegetation on farms may have helped to increase its numbers (1) (2). Reforestation within the eastern newt’s range is also believed to be benefitting this interesting amphibian (9).

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Algae
Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
Amplexus
The mating position of frogs and toads, in which the male clasps the female around the back or waist.
Carnivorous
Feeding on flesh.
Crustaceans
Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
Diurnal
Active during the day.
Gland
An organ that makes and secretes substances used by the body.
Incubate
To keep eggs warm so that development is possible.
Invertebrates
Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
Larva
Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.
Molluscs
A diverse group of invertebrates, mainly marine, that have one or all of the following: a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
Nocturnal
Active at night.
Spermatophore
A capsule or mass of sperm transferred from a male to a female during mating, for example in certain insects, arthropods and cephalopods (octopuses and squids).
Subspecies
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
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References

  1. IUCN Red List (October, 2013)
    http://www.iucnredlist.org/
  2. Jensen, J.B. (2008) Amphibians and Reptiles of Georgia. University of Georgia Press, Athens, Georgia.
  3. Holman, J.A. (2012) The Amphibians and Reptiles of Michigan: A Quaternary and Recent Faunal Adventure. Wayne State University Press, Detroit, Michigan.
  4. Illinois Natural History Survey - Eastern newt (November, 2013)
    http://www.inhs.illinois.edu/animals_plants/herps/species/no_virides.html
  5. DeVere Burton, L. (2009) Fish & Wildlife: Principles of Zoology and Ecology. Cengage Learning, Connecticut.
  6. New York State Department of Environmental Conservation - Eastern (red-spotted) newt (November, 2013)
    http://www.dec.ny.gov/animals/67022.html
  7. Virginia Department of Game and Inland Fisheries - Red-spotted newt (November, 2013)
    http://www.dgif.virginia.gov/wildlife/information/?s=020065
  8. Indiviglio, F. (2010) Newts and Salamanders. Barron’s Educational Series, Hauppauge, New York.
  9. AmphibiaWeb (November, 2013)
    http://amphibiaweb.org/
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Image credit

Terrestrial red eft form of eastern newt  
Terrestrial red eft form of eastern newt

© John Cancalosi / www.ardea.com

Ardea wildlife pets environment
59 Tranquil Vale
London
SE3 0BS
United Kingdom
Tel: +44 (0) 208 318 1401
ardea@ardea.co.uk
http://www.ardea.com

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