
Friday 25 January
Kingdom | Animalia |
Phylum | Chordata |
Class | Amphibia |
Order | Caudata |
Family | Salamandridae |
Genus | Notophthalmus (1) |
The eastern newt (Notophthalmus viridescens) is a small salamander
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).
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).
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).
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).
The eastern newt is classified as Least Concern (LC) on the IUCN Red List (1).
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).
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).
Find out more about the eastern newt:
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
Image credit
© 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
Link to this photo
Embed this Arkive thumbnail link ("portlet") by copying and pasting the code below.
Terms of Use - The displayed portlet may be used as a link from your website to Arkive's online content for private, scientific, conservation or educational purposes only. It may NOT be used within Apps.
Read more about
MyARKive
MyARKive offers the scrapbook feature to signed-up members, allowing you to organize your favourite Arkive images and videos and share them with friends.
Play the Team WILD game:
Team WILD, an elite squadron of science superheroes, needs your help! Your mission: protect and conserve the planet’s species and habitats from destruction.