The aquatic larvae have laterally compressed tails, olive colored skin, and feathery gills. The hatchlings range in length from 7 to 9mm and have fairly smooth skin with little toxicity. Although the length of the larval period and the size at metamorphosis varies, they usually transform into a terrestrial "eft" stage after 2 to 5 months. The eft is reddish-orange in color with two rows of black-bordered red spots. It has well-developed lungs, limbs, and eyelids. The eft's skin is dry and somewhat rough and its color is a sign of its toxicity to predators. The eft has a long-slender body with a laterally flattened tail and ranges in length from 3.4 to 4.5 cm. The eft usually transforms into the mature, breeding stage after 2 to 3 years on land. The adult newt varies in color depending on its age and sex, ranging from yellowish-brown to greenish-brown dorsally and have black-bordered red spots. Its ventral color is yellow and black spots speckle the belly. The newt is slightly moist (just enough to keep its skin from drying out), with rough-scaleless skin and indistinct coastal grooves. Its size ranges in length from 7 to 12.4 cm and it has small eyes with a horizontal pupil. During the breeding season, males can be easily identified by their enlarged hind legs, with black-horny structures on the inner surfaces of their thighs and toe tips (used for gripping females during mating), swollen vents, and broadly keeled (high-wavy crest) tails.
Range length: 7 to 12.4 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous
Sexual Dimorphism: ornamentation
N. viridescens appears to be involved in a Mullerian mimicry complex, with several other salamander species possibly mimicking the red eft, with its toxic skin secretions.
This newt is capable of locating its home pond through true navigation using its olfaction and light-dependent magnetic compass.
Carnivorous throughout their lives, eastern newts use both chemical and visual cues to locate food. Adults seem to rely more on visual cues when feeding. They don't have a specialized diet, but temperature and water clarity, as well as prey density, can effect the feeding process.
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; chemical
Predators of N. viridescens include birds, mammals, fish, and other amphibians, however many of them are deterred by the newt's toxic skin secretions.
Known Predators:
Anti-predator Adaptations: aposematic ; cryptic
There is no special status listed for Notophthalmus viridescens. Newts have declined in the face of habitat degradation by humans, but remain locally common in parts of their range. Adult newts will readily colonize man-made bodies of water, even in the presence of predatory fish, as their toxic skin secretions may reduce fish predation. Researchers do believe, however, that eastern newts may be suffering at higher than normal rates from diseases caused by viruses, bacteria, and fungi, due to a variety of environmental problems including pollution. Acid precipitation and deforestation may be other cause of depleted populations.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Eastern newts have a lifespan of up to 12 to 15 years. However, mortality is high in eggs and larvae.
Range lifespan
Status: captivity: 15 (high) years.
Average lifespan
Status: captivity: 15.0 years.
Notophthalmus viridescens inhabits both deciduous and coniferous forests. Immature larvae and the adult newts live in small bodies of freshwater (ponds, small lakes, ditches, and marshes) usually with mud bottoms. Adults can survive on land if their aquatic habitat becomes unsuitable; adults may move onto land during dry periods when the water is low or to rid themselves of ectoparasites. The juvenile "eft" stage lives in lakeshore and woodland habitats and is often seen in forest litter on rainy nights.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds
Wetlands: marsh
The eastern newt, Notophthalmus viridescens, is one of only a few species in the Family Salamandridae native to North America. This newt ranges throughout most of eastern North America, from the Canadian Maritime Provinces west to the Great Lakes and south to Texas, Alabama, Georgia, and Florida (Dunn and Hagen 1999; Petranka 1998; Richmond 1997). There are four recognized subspecies: the red-spotted newt (N. v. viridescens) of the eastern and northeastern U.S. and Canada, the central newt (N. v. louisianensis) of the central states and the deep south, the broken-striped newt (N. v. dorsalis) of the Carolina coastal plains, and the peninsula newt (N. v. piaropicola) of peninsular Florida.
Biogeographic Regions: nearctic (Native )
The aquatic larvae eat small invertebrates including water fleas, snails, and beetle larvae; the terrestrial efts eat small invertebrates, mainly those found in humus and leaf litter, including snails, spring tails, and soil mites; the adult newts eat mainly midge larva and other aquatic immature stages of insects. Adults don't have a specialized diet, eating any small invertebrate that they can find.
Animal Foods: insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic crustaceans; zooplankton
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)
Eastern newts are important predators of small invertebrates in the freshwater ecosystems of eastern North America.
Leeches appear to be a major source of adult mortality. Adults will generally flee the water and begin biting or scratching themselves in an attempt to rid their bodies of these ectoparasites, however they're not always successful.
Commensal/Parasitic Species:
The eastern newt may benefit humans by helping to control the populations of aquatic insects, including mosquitoes. They are aesthetically interesting and may play an important ecological role in freshwater and woodland habitats. Eastern Newts are sometimes kept as aquarium or terrarium pets and have even been commercially collected for the pet trade. Effects of this trade on exploited populations is not well documented.
Positive Impacts: pet trade
This species does not have any significant negative economic importance.
Negative Impacts: injures humans (poisonous )
The incubation of the eggs is somewhat dependent on temperature, but generally lasts from 3 to 8 weeks. In early fall, 3 to 4 months later, the aquatic larvae lose their gills, acquire sac-like lungs (heart transforms from two chambered heart to three, capable of supporting lungs), and emerge onto land as an eft. Two to 3 years later, the eft develops a powerful, flattened tail and returns to the water to breed, as an adult, and remains there the rest of its life, if water is permanent. (Lacking permanent water, adult newts will estivate and overwinter on land and enter vernal ponds in spring to breed.) Some eastern newt populations skip the eft stage and immediately transform into breeding adults. There are some coastal populations of eastern newts that become reproductively mature while retaining a gilled "larval" form (i.e., are neotenic). In other populations, newts enter the eft stage but never undergo a complete second metamorphosis, and enter the water only to breed. Both of these latter two cases may be in response to harsher than average environmental conditions.
Development - Life Cycle: neotenic/paedomorphic; metamorphosis
The breeding season begins in late winter and lasts until early spring; at this time, the female is heavy with eggs and actively seeking a male. The courtship involves a unique form of amplexus. Females are attracted by the male's spots and he lures them to him by making fanning motions with his tail and wiggling, causing an enticing odor (a pheromone) to be released. The male positions himself above and forward of the female, gripping her sides just behind her forelegs with his hindlimbs and rubbing her snout with the side of his head. Males will deposit a sperm packet on the bottom of the pond and the female will proceed to pick it up with her cloaca, later using the sperm to fertilize her eggs. Males are often in competition with each other, but rival males who try to break up a pair already involved in amplexus are rarely successful. Sometimes the rival male may drop his sperm packet anyway and the female may pick up the packet when courtship with the other male is over. Male to male courtship is also common. Males tend to eat the sperm packets that are dropped in this case.
Mating System: polygynandrous (promiscuous)
Oviposition can take several weeks, because the female will only lay a few, widely scattered eggs, each day. It's still uncertain whether or not females will lay all of their eggs in a breeding season, however they do lay between 200 and 400 single, jelly-covered eggs on submerged vegetation, each season. As soon as the process is finished, the female newt swims away leaving her eggs to survive on their own. Both males and females reach sexual maturity around the age of 3.
Breeding interval: Eastern newts breed once per year.
Breeding season: The breeding season varies with latitude, beginning in late winter and lasting until early spring.
Range number of offspring: 200 to 400.
Range time to hatching: 3 to 8 weeks.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Average age at sexual or reproductive maturity (male)
Sex: male: 2000 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 2000 days.
Females do not provide parental care after they deposit their eggs. Males do not invest in young past sperm production and mating.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)
The eastern newt (Notophthalmus viridescens) 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.[2] It has a lifespan of 12 to 15 years in the wild, and it may grow to 5 in (13 cm) 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 (although there is no "western" one).[3][4]
The eastern newt includes these four subspecies:[5]
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.[6] 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, 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 (Brossman 2014).
The red eft (juvenile) 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 (i.e., the saturation of the eft's tissues with tetrodotoxin) to potential predators.[7] Their tetrodotoxin is a neurotoxin which is also the strongest emetic that is known.[8]
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 (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 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. 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.
They may travel far from their original location during the eft stage. 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.[9]
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,[10] 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.[11][12] 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.
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.
Eastern newts are highly sensitive to changes in their environment and are able to detect and respond to changes in water quality and temperature. This sensitivity allows them to thrive in a variety of habitats, but it also makes them vulnerable to environmental changes and pollution.[13] 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.
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. During the winter months, some eastern newts will often burrow underground or seek shelter in logs or other debris to avoid the cold.[14] However, studies have shown that some do not engage in hibernation, depending on the location of the species.[15]
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.[3] Ferromagnetic material, probably biogenic magnetite, is likely present in the eastern newt's body.[4]
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.[16] Distance travelled depended on humidity and precipitation. The mean distance traveled overnight was about 15 m, with longest trails ranging over 70 m.[17]
Eastern newts breed once per year, when breeding starts in late fall until early spring. They are known to be polygynandrous, with females and males mating with multiple partners. Males have preference towards larger females, while no evidence for female preference during mating was found.[18] The breeding migration often happens more with rainfall.[19] The male's spots attract females, luring them to him with fanning motions of his tail, causing a pheromone to be released.[20] Once the female has chosen a mate, the male will deposit a spermatophore, a package of sperm, onto the ground, which the female will then pick up and fertilize her eggs with. The female will lay her eggs in the water, attaching them to submerged vegetation or other objects. 200~400 eggs are laid in a single batch, with incubation period of 3~8 weeks.[21] For the normal and healthy development of gonads, fat-bodies are needed in proximity of the developing organs to ensure proper reproduction ability.[22]
The behavior of eastern newts is also influenced by their social interactions with other members of their species. Eastern newts exhibit social hierarchy, with dominant individuals exhibiting aggressive behaviors towards subordinates. This social hierarchy is thought to be related to the distribution of resources, with dominant individuals having access to more food and better mating opportunities. One such behavior is territoriality, where individuals will defend a specific area or resource from other members of their species. This behavior is commonly seen in males during the breeding season, when they will defend a territory in order to attract females and ensure access to mating opportunities.
Secretion of toxins through the skin protects the newt from predators, and should therefore not be handled with bare hands. The red colors of the adult newt also act as a warning sign for predators.[23] Its ventral surface has poison glands, which makes predators reluctant to eat it.[24] However, one study observed a Belted Kingfisher (Megaceryle alcyon) beat an eastern newt on a nest box 15 times before eating it.[25] This special toxin is known as tetrodotoxin. Several studies have found that newt larvae increase the production of this toxin while in the presence of predators (dragonflies). Tetrodotoxin is known to cause muscle paralysis, skin irritation, and even death in predators, although some species mantis species have shown a resilience to this toxin.[26] The Eastern newt also has a greater tail depth and is capable of swimming quickly away from aquatic predators.
Eastern newts are able to regenerate their limbs that were lost to an injury. Forelimb regeneration has been considered to be close to the forelimb development; genes that play a role in forelimb regeneration are known to also be expressed in its developmental stages.[27] In addition. they are capable of regenerating their spinal cord, heart, and other organs. This ability is thought to be related to their high levels of stem cells, which allow them to repair and regenerate damaged tissues.[28]
Although eastern newts are widespread throughout North America, they, like many other species of amphibians, are increasingly threatened by several factors including habitat fragmentation, climate change, invasive species, over-exploitation, and emergent infectious diseases.[29] The biodiversity of amphibians across the United States is considered to be threatened due to the loss of wetlands and furthermore, their connectivity;[30][31] since the 1780s, more than 53% of wetlands in the United States have been lost.[32] For example, a study found the toxicity of coal-tar pavement on eastern newts sublethal, decreasing their righting ability and swimming speed.[33] Wild eastern newts are known hosts of Batrachochytrium dendrobatidis and Ranavirus, as well as the mesomycetozoan Amphibiocystidium ranae[34]. They are also highly susceptible to the newly emergent chytrid fungus Batrachochytrium salamandrivorans.[35]
Terrestrial juvenile stage ("red eft")
Aquatic larval stage
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Eft near Northfield, Massachusetts
Eft navigating over leaves near Thomasville, Alabama
Eft on North Fork Mountain in eastern West Virginia
Eft seen along a trail in Harriman Park, New York
Swollen cloaca and large hind legs in a reproductive adult male
Adult female central newt
_Sept_2018.jpg)
A red-spotted newt among the autumn leaves not far from Bolton, Vermont
The eastern newt (Notophthalmus viridescens) 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 5 in (13 cm) 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 (although there is no "western" one).
