The eastern newt (''Notophthalmus viridescens'') is a common
newt
A newt is a salamander in the subfamily Pleurodelinae. The terrestrial juvenile phase is called an eft. Unlike other members of the family Salamandridae, newts are semiaquatic, alternating between aquatic and terrestrial habitats. Not all aqua ...
of eastern
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
. It frequents small lakes, ponds, and streams or nearby wet forests. The eastern newt produces
tetrodotoxin
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered ...
, which makes the species unpalatable to predatory fish and
crayfish
Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...
.
It has a lifespan of 12 to 15 years in the wild, and it may grow to in length. These animals are common
aquarium
An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...
pet
A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive appearances, intelligence, ...
s, 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).
Subspecies
The eastern newt includes these four subspecies:
*Red-spotted newt (''Notophthalmus viridescens viridescens'')
*Broken-striped newt (''Notophthalmus viridescens dorsalis'')
*Central newt (''Notophthalmus viridescens louisianensis'') - 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 (''Notophthalmus viridescens piaropicola'')
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: (1) the aquatic
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
or
tadpole
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found i ...
, (2) the red eft or terrestrial juvenile stage, and (3) the aquatic adult.
Larva
The larva possesses
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...
s 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.
Red eft
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
Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity.
Outcrossing can be a useful ...
in the population. The striking coloration of this stage is an example of
aposematism
Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or ...
— or "warning coloration" — which is a type of
antipredator adaptation
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avo ...
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
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
.
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
Olive is a dark yellowish-green color, like that of unripe or green olives.
As a color word in the English language, it appears in late Middle English. Shaded toward gray, it becomes olive drab.
Variations
Olivine
Olivine is the typical ...
dorsally, with a dull yellow belly, but retains the eft's characteristic black-rimmed red spots. It develops a larger, blade-like
tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...
and characteristically slimy skin.
It is common for the peninsula newt (''N. v. piaropicola'') to be
neotenic
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...
, 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
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant ...
and
deciduous forests
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, afte ...
. 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
''Sarracenia purpurea'', the purple pitcher plant, northern pitcher plant, turtle socks, or side-saddle flower, is a carnivorous plant in the family Sarraceniaceae.
Description
Like other species of ''Sarracenia'', ''S. purpurea'' obtains most ...
''.
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
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of j ...
,
springtails
Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Ent ...
, soil mites, small
mollusks
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
and
crustaceans
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
, young
amphibians
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbore ...
, worms, and
frog
A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
. 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. 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.
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. 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
A home, or domicile, is a space used as a permanent or semi-permanent residence for one or many humans, and sometimes various companion animals. It is a fully or semi sheltered space and can have both interior and exterior aspects to it. H ...
using magnetic orientation. Their
magnetoreception
Magnetoreception is a sense which allows an organism to detect the Earth's magnetic field. Animals with this sense include some arthropods, molluscs, and vertebrates (fish, amphibians, reptiles, birds, and mammals, though not humans). The se ...
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
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...
s 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
Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...
material, probably
biogenic
A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of p ...
magnetite
Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the ...
, 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 travelled depended on humidity and precipitation. The mean distance traveled overnight was about 15 m, with longest trails ranging over 70 m.
Reproduction
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. The breeding migration often happens more with rainfall. The male's spots attract females, luring them to him with fanning motions of his tail, causing a pheromone to be released. 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.
Social interactions
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.
Survival advantages
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. Its ventral surface has poison glands, which makes predators reluctant to eat it. 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. The Eastern newt also has a greater tail depth and is capable of swimming quickly away from aquatic predators.
Limb regeneration
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. 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.
Conservation concerns
Although eastern newts are widespread throughout North America, they, like many other species of amphibians, are increasingly threatened by several factors including
habitat fragmentation
Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes ...
,
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
,
invasive species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
, over-exploitation, and
emergent infectious diseases. The biodiversity of amphibians across the United States is considered to be threatened due to the loss of wetlands and furthermore, their connectivity; since the 1780s, more than 53% of wetlands in the United States have been lost. For example, a study found the toxicity of coal-tar pavement on eastern newts sublethal, decreasing their righting ability and swimming speed.
Wild eastern newts are known hosts of ''
Batrachochytrium dendrobatidis
''Batrachochytrium dendrobatidis'' ( ), also known as ''Bd'' or the amphibian chytrid fungus, is a fungus that causes the disease chytridiomycosis in amphibians.
Since its discovery in 1998 by Lee Berger, the disease devastated amphibian popul ...
'' and ''
Ranavirus
''Ranavirus'' is a genus of viruses, in the family ''Iridoviridae''. There are six other genus, genera of viruses within the family ''Iridoviridae'', but ''Ranavirus'' is the only one that includes viruses that are infectious to amphibians and ...
''. They are also highly susceptible to the newly emergent
chytrid
Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek ('), meaning "little pot", describing the structure containing unreleased zoöspores. Chytrid ...
fungus ''
Batrachochytrium salamandrivorans
''Batrachochytrium salamandrivorans'' (''Bsal'') is a pathogenic chytrid fungus that infects amphibian species. Although salamanders and newts seem to be the most susceptible, some anuran species are also affected. ''Bsal'' has emerged recent ...
''.
Gallery
File:Notophthalmus viridescensPCCA20040816-3983A.jpg, Terrestrial juvenile stage ("red eft")
File:Circ1258 plates 17b.jpg, Aquatic larval stage
File:Red-spotted newt (N. v. viridescens).jpg, Eft near Northfield, Massachusetts
File:Red spotted newt 01.JPG, Eft navigating over leaves near Thomasville, Alabama
File:Eastern newt red eft stage Sep 3 2012 North Fork Mountain near Chimney Top.jpg, Eft on North Fork Mountain
North Fork Mountain is a quartzite-capped mountain ridge in the Ridge and Valley physiographic province of the Allegheny Mountains (or "High Alleghenies" or "Potomac Highlands") of eastern West Virginia. Kile Knob, at 4,588 feet (1,398 m), is th ...
in eastern West Virginia
File:Eastern red-spotted newt.jpg, Eft seen along a trail in Harriman Park, New York
File:Notophthalmus viridescens adult male 3.jpg, Swollen cloaca and large hind legs in a reproductive adult male
File:Notophthalmus viridescens adult female.jpg, Adult female central newt
File:Red-spotted newt (Vermont) Sept 2018.jpg, A red-spotted newt among the autumn leaves not far from Bolton, Vermont
Bolton is a town in Chittenden County, Vermont, United States. The population was 1,301 at the time of the 2020 census. The town is home to Bolton Valley, a popular ski resort.
The main road passing through the town is U.S. Route 2, which follo ...
References
Citations
Further reading
*
*
External links
*
*
''Notophthalmus viridescens''.Animal Diversity Web.
Checklist of Amphibian Species and Identification Guide. USGS Northern Prairie Wildlife Research Center.
Red-spotted Newt (''Notophthalmus viridescens viridescens'').Virginia Department of Game and Inland Fisheries.
Eastern Newt Caresheet and Photos.Caudata Culture.
''Notophthalmus viridescens'' Species Account.AmphibiaWeb.
Central Newt on Reptiles and Amphibians of Iowa
{{Taxonbar, from=Q1552306
Amphibians of Canada
Amphibians of the United States
Amphibians described in 1820
Cenozoic amphibians of North America
Ecology of the Appalachian Mountains
Extant Pleistocene first appearances
Fauna of the Great Lakes region (North America)
Fauna of the Northeastern United States
Fauna of the Plains-Midwest (United States)
Fauna of the Southeastern United States
Newts
Pleistocene animals of North America
Pleistocene United States
Taxa named by Constantine Samuel Rafinesque