The smooth newt, European newt, northern smooth newt or common newt (Lissotriton vulgaris ) is a species of newt. It is widespread in Europe and parts of Asia, and has been introduced into Australia. Individuals are brown with a spotted underside that ranges in color from orange to white. They reach an average length of 8–11 cm (3.1–4.3 in); males are larger than females. The newts' skins are dry and velvety when they are living on land, but become smooth when they migrate into the water to breed. Males develop a more vivid colour pattern and a conspicuous skin seam (crest) on their back when breeding.
The smooth newt was originally described by Carl Linnaeus as a lizard, and was then given different genus names before the adoption of its current classification as a member of Lissotriton. There are currently three accepted subspecies of smooth newt. Formerly, there were also four subspecies—all with more restricted ranges—that are now classified as separate species, because they have been found to be distinct genetically as well as in appearance: the Caucasian smooth newt, the Greek smooth newt, Kosswig's smooth newt and Schmidtler's smooth newt. Together with these four species and the Carpathian newt, the smooth newt forms what is known as a species complex: some of the species hybridise with each other.
For most of the year, smooth newts live on land, are mostly nocturnal, and hide during the day. They can adapt to a wide range of natural or semi-natural habitats, from forests at field edges to parks and gardens. They feed mainly on invertebrates such as insects and earthworms and are themselves eaten mainly by fish, birds and snakes. Between spring and summer, they breed in ponds or similar bodies of water. Males court females with a ritualised underwater display. Females lay their eggs on water plants, and larvae hatch after 10 to 20 days. The larvae develop for around three months before metamorphosing into terrestrial juveniles, at which point they become known as efts. They reach maturity after two to three years, and the adults live for up to 14 years.
The smooth newt is abundant over much of its range and is classified as a species of least concern by the International Union for Conservation of Nature (IUCN). It has been negatively affected by habitat destruction and fragmentation and by the introduction of new species of fish. Like other European amphibians, the smooth newt has now been listed as a protected species by the Berne Convention.
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starts withAdult males of the smooth newt reach around 9–11 cm (3.5–4.3 in) head-to-tail length and are thus slightly larger than the females, which reach 8–9.5 cm (3.1–3.7 in). The body weight of adults varies between 0.3–5.2 g (0.011–0.183 oz), and decreases during the breeding season. The head is longer than it is wide, with 2–3 longitudinal grooves on the top, and the elongated snout is blunt in the male and rounded in the female. The skin is velvety and water-repellent on land but smooth during the aquatic phase; it contains mucus and toxin glands and its upper layer is shed off regularly.: 80–93 : 233–234
Outside the breeding season, both sexes are yellow-brown, brown or olive-brown. The male has dark, round spots, while the female has smaller spots of the same colour, which sometimes form two or more irregular lines along the back. The male has an orange strip on the tail underside, and the throat and belly in males are orange to white with small dark, rounded spots (these are lighter with smaller spots in the female). Size and colour vary with the environment, and the newts tend to be smaller in northern latitudes.: 80–93 : 233–234 Albinistic and leucistic individuals have been described.: 94
The smooth newt is diploid (i.e. it has two copies of each chromosome), with 24 chromosomes in total.: 107
In the Carpathians, the smooth newt generally prefers lower elevations than the Carpathian newt. In the Balkans, the precise contact zones with the Greek smooth newt and Schmidtler's smooth newt are not yet clear. In central Italy, where the range of the smooth newt subspecies L. v. meridionalis overlaps with that of the Italian newt (L. italicus ), it was found that the latter prefers a warmer and drier climate.
the central Balkans and the dry Eurasian steppe of Ukraine and Russia.: 234–238 : 42–44 The subspecies L. v. ampelensis only occurs in the Carpathians of Ukraine and the Danube delta of northern Romania, and L. v. meridionalis in the northern half of Italy, southern Switzerland, Slovenia and Croatia.: 234–235
In the Carpathians, the smooth newt generally prefers lower elevations than the Carpathian newt. In the Balkans, the precise contact zones with the Greek smooth newt and Schmidtler's smooth newt are not yet clear. In central Italy, where the range of the smooth newt subspecies L. v. meridionalis overlaps with that of the Italian newt (L. italicus ), it was found that the latter prefers a warmer and drier climate.
The nominate subspecies, L. v. vulgaris, has been introduced to Australia, which has no native salamander species. The smooth newt was available in the Australian pet trade until 1997, when it was declared a "controlled pest animal" because of the risk of introduction. The first record in the wild was made near Melbourne in 2011, and larvae were later found, indicating successful reproduction. Negative impacts on the native fauna are feared, including predation on and competition with native frogs and freshwater invertebrates, toxicity, and disease spread. The smooth newt could spread further in south-eastern Australia, where wide areas have a suitable climate.
Within Europe, the subspecies L. v. meridionalis was introduced north of the Alps near Geneva, where it hybridises with the native L. v. vulgaris.
Mainly a lowland species, the smooth newt is only exceptionally found above 1,000 m (3,300 ft).: 78–80 Thes species shows a wide habitat breadth, as it's able to thrive in a wide array of terrestrial and aquatic environments. On land, it occurs in wooded areas (dense conifer woods are avoided) but also in more open areas such as damp meadows, field edges, parks and gardens. It can also tolerate human disturbance and urban environments. The newts hide under structures such as logs or stones or in small mammal burrows.: 120–134 : 238
Freshwater breeding sites are typically sun-exposed, free from fish, stagnant, water-filled permanently or for at least three months of the year, close to similar water bodies, and have shallow areas with abundant water plants. They can range from small puddles to larger ponds or shallow parts of lakes. Water quality is less important; pH values from 4 (more acidic) to 9.6 (more alkaline) are tolerated and in Germany, smooth newts have even been found in slightly brackish water.: 121–129 They often share breeding sites with other amphibians, including other newts; in northern France, ponds with five newt species – smooth, palmate, alpine, northern crested and marbled (T. marmoratus ) newt – have been described.: 151–152
Smooth newts live on land during most of the year and are mainly nocturnal. They also usually hibernate on land, often in congregations of several newts in winter shelters such as under logs or in burrows (but they can be active during mild weather). The efts turn into mature adults at two to three years, and the newts can reach an age of 6–14 years in the wild.: 238 The newts recognise familiar territory using smell and visual cues, but could not orient themselves in experiments when they were transported far away from the home range.
Smooth newts, including the larvae, are unselective carnivores, feeding mainly on diverse invertebrates such as earthworms, snails or insects, or smaller plankton. Cannibalism also occurs, mainly by preying on eggs of its own species. Various predators eat smooth newts, including waterbirds, snakes and frogs, but also larger newts such as the northern crested newt.: 238
Various pathogens and parasites have been found to infect smooth newts, including ranaviruses, a picornavirus, various protozoans,: 164 trematodes: 164 (of which Parastrigea robusta was found to cause the local decline of a population in Germany) and at least 31 species of helminths.
During the aquatic breeding season, males develop a skin seam or crest, which runs uninterrupted along the back and the tail. It is 1–1.5 mm (0.039–0.059 in) high at mid-body, but higher along the tail. The tail also has a lower fin, and its end is pointed. The cloaca (the single digestive, urinary and reproductive orifice) of breeding males is swollen, round and dark-coloured. The hindfeet have more or less developed toe flaps, depending on the subspecies. Colours in general are more vivid than during the land phase. The dark spots grow larger, and the crest often has vertical dark and bright bands. There are five to seven longitudinal stripes on the head. The lower edge of the tail is red with a silver-blue flash and black spots. Females only develop low, straight tail fins but no crest or toe flaps, and are more drably coloured.: 26 : 233–234
Subspecies differ slightly in male secondary characteristics: L. v. ampelensis has strongly developed toe flaps, its tail tapers into a fine thread (but not a distinct filament), and the body is slightly square in cross-section. L. v. meridionalis also has toe flaps and a pointed tail, its crest is smooth-edged, and its body is square-shaped. In the nominate subspecies, L. v. vulgaris, the crest is clearly denticulated, toe flaps are only weakly developed and the body is round.: 234–236
Migration to the breeding sites occurs as soon as February, but in the northern parts of the range and at higher altitudes, it may not start before summer. After entering the water, the breeding characters, especially the male's crest, take a few weeks to develop.: 238
Mating involves an intricate courtship display: the male attempts to attract a female by swimming in front of her and sniffing her cloaca. He then vibrates his tail against his body, sometimes violently lashing it, thereby fanning pheromones towards her. In the final phase, he moves away from her, the tail quivering. If she is still interested, she will follow him and touch his cloaca with her snout, whereupon he deposits a packet of sperm (a spermatophore). He then guides her over the spermatophore so she picks it up with her cloaca. Males often try to lead females away from displaying competitors.: 238–240
Eggs are fertilised internally, and progeny of one female usually has multiple fathers. Females tend to mate preferentially with unrelated males, probably to avoid inbreeding depression.
Females lay 100–500 eggs, usually folding them into waterplants. The eggs are 1.3–1.7 mm (0.051–0.067 in) in diameter (2.7–4 mm (0.11–0.16 in) with jelly capsule) and light brown to greenish or grey in colour. Larvae typically hatch after 10–20 days, depending on temperature, and metamorphose into terrestrial efts after around three months.: 238–240
Paedomorphism, where adults stay aquatic and retain their gills and skin seams or only resorb them partially, occurs regularly but only in a small proportion of individuals. It does not appear to be determined genetically but favoured by cold water, a low density of individuals and abundant aquatic prey. Wild paedomorphic individuals often metamorphosed when they were transferred into an aquarium.: 192–193
