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Eastern newt | |
---|---|
Aquatic adult male | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | Urodela |
Family: | Salamandridae |
Genus: | Notophthalmus |
Species: | N. viridescens |
Binomial name | |
Notophthalmus viridescens (Rafinesque, 1820) | |
Range of N. viridescens subspecies: Yellow: N. v. viridescens Contents |
Eastern newts are 1'inch long 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 stage is a period of 2 to 5 months. [7] 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. [8] Their tetrodotoxin is a neurotoxin which is also the strongest emetic that is known. [9] Sometimes the juvenile will continue its aquatic existence also after metamorphosis. [10]
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. Habitat preferences include shallow water, quiet stretches of streams, swamps or ditches, lakes and ponds with heavy submerged vegetation. and nearby damp woodlands. [11] 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 53 °F (12 °C)—and will hide under leaf litter in dry weather. [12] 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 . [13]
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. [14] They also eat a lot of snails, beetles, ants, and mosquito larvae, with an annual ingestion of about 35,000 kcal. [15] [16] 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. [17] 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. [18]
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. [19] During the winter months, some eastern newts will often burrow underground or seek shelter in logs or other debris to avoid the cold. [20] However, studies have shown that some do not engage in hibernation, depending on the location of the species. [21]
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. [22] Distance traveled depended on humidity and precipitation. The mean distance traveled overnight was about 15 m, with longest trails ranging over 70 m. [23]
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. [24] The breeding migration often happens more with rainfall. [25] The male's spots attract females, luring them to him with fanning motions of his tail, causing a pheromone to be released. [26] 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. [27] For the normal and healthy development of gonads, fat-bodies are needed in proximity of the developing organs to ensure proper reproduction ability. [28]
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. [29] Its ventral surface has poison glands, which makes predators reluctant to eat it. [30] However, one study observed a Belted Kingfisher (Megaceryle alcyon) beat an eastern newt on a nest box 15 times before eating it. [31] 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 mantis species have shown a resilience to this toxin, [32] and predatory sunfish are not deterred by the toxin. [33] 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. [34] 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. [35]
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. [36] The biodiversity of amphibians across the United States is considered to be threatened due to the loss of wetlands and furthermore, their connectivity; [37] [38] since the 1780s, more than 53% of wetlands in the United States have been lost. [39] For example, a study found the toxicity of coal-tar pavement on eastern newts sublethal, decreasing their righting ability and swimming speed. [40] Wild eastern newts are known hosts of Batrachochytrium dendrobatidis and Ranavirus, as well as the mesomycetozoan Amphibiocystidium ranae [41] . They are also highly susceptible to the newly emergent chytrid fungus Batrachochytrium salamandrivorans . [42]
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods excluding the amniotes. All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura, Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater, wetland or terrestrial ecosystems. Their life cycle typically starts out as aquatic larvae with gills known as tadpoles, but some species have developed behavioural adaptations to bypass this.
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Urodela is a scientific Latin term based on the Ancient Greek οὐρά δήλη: ourà dēlē "conspicuous tail". Caudata is the Latin for "tailed ones", from cauda: "tail".
The palmate newt is a species of newt found in Western Europe, from Great Britain to the northern Iberian Peninsula. It is 5–9.5 cm (2.0–3.7 in) long and olive or brown with some dark spots. The underside is yellow to orange, and the throat, unlike in the similar smooth newt, always unspotted. A dark stripe runs along the head and through the eyes. Breeding males develop a distinct filament on the end of their tail, strongly webbed hind feet, and a low, smooth crest on their back.
Amplexus is a type of mating behavior exhibited by some externally fertilizing species in which a male grasps a female with his front legs as part of the mating process, and at the same time or with some time delay, he fertilizes the eggs, as they are released from the female's body. In amphibians, females may be grasped by the head, waist, or armpits, and the type of amplexus is characteristic of some taxonomic groups.
The spotted salamander or yellow-spotted salamander is a mole salamander common in eastern United States and Canada. It is the state amphibian of Ohio and South Carolina. The species ranges from Nova Scotia, to Lake Superior, to southern Georgia and Texas. Its embryos have been found to have symbiotic algae living in and around them, the only known example of vertebrate cells hosting an endosymbiont microbe.
The northern crested newt, great crested newt or warty newt is a newt species native to Great Britain, northern and central continental Europe and parts of Western Siberia. It is a large newt, with females growing up to 16 cm (6.3 in) long. Its back and sides are dark brown, while the belly is yellow to orange with dark blotches. Males develop a conspicuous jagged crest on their back and tail during the breeding season.
The alpine newt is a species of newt native to continental Europe and introduced to Great Britain and New Zealand. Adults measure 7–12 cm (2.8–4.7 in) and are usually dark grey to blue on the back and sides, with an orange belly and throat. Males are more conspicuously coloured than the drab females, especially during breeding season.
Triturus is a genus of newts comprising the crested and the marbled newts, which are found from Great Britain through most of continental Europe to westernmost Siberia, Anatolia, and the Caspian Sea region. Their English names refer to their appearance: marbled newts have a green–black colour pattern, while the males of crested newts, which are dark brown with a yellow or orange underside, develop a conspicuous jagged seam on their back and tail during their breeding phase.
The ringed salamander is a species of mole salamander native to hardwood and mixed hardwood-pine forested areas in and around the Ozark Plateau and Ouachita Mountains of Arkansas, Oklahoma, and Missouri. This species of salamander has slander body, small head, and long tail. They are usually found to have various dorsal color from dark gray to dark brown. Various close relatives are found such as marbled salamander and spotted salamander. This species of salamander has cannibal behavior especially those in large body size.
The genus Taricha consists of four species of highly toxic newts in the family Salamandridae. Their common name is Pacific newts, sometimes also western newts or roughskin newts. The four species within this genus are the California newt, the rough-skinned newt, the red-bellied newt, and the sierra newt, all of which are found on the Pacific coastal region from southern Alaska to southern California, with one species possibly ranging into northern Baja California, Mexico.
The Iberian ribbed newt, gallipato or Spanish ribbed newt is a newt endemic to the central and southern Iberian Peninsula and Morocco. It is the largest European newt species and it is also known for its sharp ribs which can puncture through its sides, and as such is also called the sharp-ribbed newt.
Notophthalmus meridionalis, the black-spotted newt or Texas newt, is a species of aquatic newt native to northeastern Mexico and southern Texas in the United States. This amphibian was put on the IUCN Red List of Endangered Species in 2008 with populations still decreasing. It was reclassified to Vulnerable in 2022.
The lesser siren is a species of aquatic salamander native to the eastern United States and northern Mexico. They are referred to by numerous common names, including two-legged eel, dwarf siren, and mud eel. The specific epithet intermedia denotes their intermediate size, between the greater siren, Siren lacertina, and the dwarf sirens, Pseudobranchus species.
The striped newt is a species of aquatic salamander native to the southeastern United States. It is a close relative of the eastern newt, with which it shares territory, and can be distinguished from the latter by the presence of red stripes running down the sides of its back and red spots on its back that lack a black outline.
Desmognathus fuscus is a species of amphibian in the family Plethodontidae. The species is commonly called the dusky salamander or northern dusky salamander to distinguish it from populations in the southern United States which form several distinct species, the southern dusky salamanders. The northern dusky salamander is the most widespread representative of its genus in Canada. It can be found in eastern North America from extreme eastern Canada in New Brunswick south to South Carolina. The size of the species' total population is unknown, but is assumed to easily exceed 100,000. The species' habitat differs somewhat geographically; dusky salamanders in the northern part of the range prefer rocky woodland streams, seepages, and springs, while those in the south favor floodplains, sloughs, and muddy places along upland streams. They are most common where water is running or trickling. They hide under various objects, such as leaves or rocks, either in or near water. Alternatively, they may enter burrows for protection. The dusky salamander lays its eggs close to water under moss or rocks, in logs, or in stream-bank cavities. The larval stage which follows is normally aquatic.
The mud salamander is a bright red salamander of the family Plethodontidae. It is found in streams, seeps and swamps and underneath logs, rocks and leaves. It is endemic to the eastern half of the United States with one isolated population in central Mississippi. Mud salamanders are rarely seen plethodontids that inhabit muddy wetland and riparian habitats. Mud salamanders don’t generally live above 700 meters in elevation in the Appalachian Mountains, resulting in two geographically isolated populations. Mud salamanders have short stocky bodies ranging from 7.5 to 16 cm long. Body color ranges with age and locality. There are four subspecies in the mud salamander complex, namely the Gulf Coast mud salamander, rusty mud salamander, Midland mud salamander and the eastern mud salamander. Mud salamanders are ectothermic, meaning that they cannot control their body temperature and it fluctuates with the temperature. The mud salamander is readily confused with two other species, the red salamander and the spring salamander.
The red salamander is a species of salamander in the family (Plethodontidae) endemic to the eastern United States. Its skin is orange/red with random black spots. Its habitats are temperate forests, small creeks, ponds, forests, temperate shrubland, rivers, intermittent rivers, freshwater, trees springs. Overall this species is common and widespread, but locally it has declined because of habitat loss and it is considered threatened in Indiana and New York. Red salamanders eat insects, earthworms, spiders, small crustaceans, snails, and smaller salamanders. To eat, they extend their tongue to capture prey on the tip of it and retract it back into their mouths. The red salamander, as a member of the family Plethodontidae lacks lungs and respires through its skin.
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 aquatic salamanders are considered newts, however. More than 100 known species of newts are found in North America, Europe, North Africa and Asia. Newts metamorphose through three distinct developmental life stages: aquatic larva, terrestrial juvenile (eft), and adult. Adult newts have lizard-like bodies and return to the water every year to breed, otherwise living in humid, cover-rich land habitats.
Poisonous amphibians are amphibians that produce toxins to defend themselves from predators.