Eastern newt
The eastern newt is a common newt of eastern North America. It frequents small lakes, ponds, and streams or nearby wet forests. The eastern newt produces tetrodotoxin, which makes the species unpalatable to predatory fish and crayfish. It has a lifespan of 12 to 15 years in the wild, and it may grow to in length. These animals are common aquarium pets, being either collected from the wild or sold commercially. The striking bright orange juvenile stage, which is land-dwelling, is known as a red eft. Some sources blend the general name of the species and that of the red-spotted newt subspecies into the eastern red-spotted newt.
Subspecies
The eastern newt includes these four subspecies:- Red-spotted newt
- Broken-striped newt
- Central newt - Central newts measure from to in length. They are brown or green, with fine black dots all over the body. There may be a row of red spots on each side of the body. The belly is yellow or orange and is noticeably lighter than the rest of the body. The skin of newts is not as slippery as the skin of salamanders and may appear to be rough and dry for parts of their lives.
- Peninsula newt
Life stages
Eastern newts have a lifespan of about 8–10 years in the wild, but some individuals have been known to live up to 15 years. Eastern newts have three stages of life: the aquatic larva or tadpole, the red eft or terrestrial juvenile stage, and the aquatic adult.Larva
The larva stage is a period of 2 to 5 months. The larva possesses gills and does not leave the pond environment where it was hatched. Larvae are brown-green, and shed their gills when they transform into the red eft. The larval Eastern Newt is the most heavily preyed upon stage. They are commonly predated on by fish, aquatic insects, and other adult newts.Red eft
The red eft stage is a bright orangish-red, 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. An eastern newt's time to get from larva to eft is about three months. During this stage, the eft may travel far, acting as a dispersal stage from one pond to another, ensuring outcrossing in the population. The striking coloration of this stage is an example of aposematism — or "warning coloration" — which is a type of antipredator adaptation in which a "warning signal" is associated with the unprofitability of a prey item to potential predators. Their tetrodotoxin is a neurotoxin which is also the strongest emetic that is known. Sometimes the juvenile will continue its aquatic existence also after metamorphosis.Adult
After two or three years, the eft finds a pond and transforms into the aquatic adult. The adult's skin is a dull olive green dorsally, with a dull yellow belly, 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 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.
Habitat
Eastern newts are at home in both coniferous and deciduous forests. Habitat preferences include shallow water, quiet stretches of streams, swamps or ditches, lakes and ponds with heavy submerged vegetation. and nearby damp woodlands. They need a moist environment with either a temporary or permanent body of water, and thrive best in a muddy environment. Eastern newts have a preference for certain types of habitats, with males preferring more open, aquatic habitats and females preferring more forested, terrestrial habitats. This preference may be related to the different roles that males and females play in the reproductive process, with males typically being more active in courtship and females spending more time on land preparing to lay eggs.Eastern newts may travel far from their original location during the eft stage. They are most active during warm rainy periods—warmer than —and will hide under leaf litter in dry weather. 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.
Diet
Eastern newts are carnivorous, feeding on a variety of prey every two to three days. As larvae, they feed on small aquatic invertebrates, and as adults, they eat insects, worms, snails, and other small invertebrates. Eastern newts eat a variety of prey, such as insects, springtails, soil mites, small mollusks and crustaceans, young amphibians, worms, and frog eggs. They also eat a lot of snails, beetles, ants, and mosquito larvae, with an annual ingestion of about 35,000 kcal. Their dietary habits prove to be beneficial to humans because they help to control insect populations and maintain balance to their habitats. Eastern newts are a vital part of many ecosystems, serving as both predators and prey.Behavior
Eastern newts have a number of natural predators, including fish, snakes, birds, and larger salamanders. They have several defenses against these predators, including their bright coloring, which serves as a warning signal, and their ability to secrete toxins from their skin as a defense mechanism.Adaptability
Eastern newts are highly sensitive to changes in their environment and are able to detect and respond to changes in water quality and temperature. They will follow the thermoclines of their habitats as it changes with the seasons.This sensitivity allows them to thrive in a variety of habitats, but it also makes them vulnerable to environmental changes and pollution. In fact, eastern newts are considered a sensitive species, meaning that they are often used as indicators of ecosystem health. When populations of eastern newts decline, it can be a sign of environmental stress or degradation. Newt populations are threatened by deforestation, habitat fragmentation, and pollution.Hibernation
Eastern newts are ectothermic, relying on external sources of heat to regulate their body temperature. They are most active during the warmer months of the year, but they can also be found in more temperate climates where they may be active year-round. Eastern Newts have showcased a resistance to a wide variety of temperatures, altering their body chemistry and being able to survive and breed even under ice in winter conditions. During the winter months, some eastern newts will often burrow underground or seek shelter in logs or other debris to avoid the cold. However, studies have shown that some do not engage in hibernation, depending on the location of the species.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. Ferromagnetic material, probably biogenic magnetite, is likely present in the eastern newt's body.A study determined that the home range size for Eastern newts is primarily affected by food availability, substrate humidity, but not affected by dispersal ability, competition, shelter availability, or predator avoidance. Distance traveled depended on humidity and precipitation. The mean distance traveled overnight was about 15 m, with longest trails ranging over 70 m.