Viviparous lizard

Zootoca vivipara
Conservation status
Least Concern  (IUCN 3.1) [1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Family:	Lacertidae
Tribe:	Lacertini
Genus:	Zootoca Wagler, 1830
Species:	Z. vivipara
Binomial name
Zootoca vivipara (Lichtenstein, 1823)[2]
Synonyms
Lacerta vivipara Lichtenstein, 1823

The viviparous lizard or common lizard, Zootoca vivipara (formerly Lacerta vivipara), is a Eurasian lizard. It lives farther north than any other reptile species, and most populations are viviparous (giving birth to live young), rather than laying eggs as most other lizards do. It is the only species in the monotypic genus Zootoca.^[3]

Identification

The length of the body is less than 12 cm (5 in) (excluding the tail). The tail is up to twice as long as the body, although it is often partially or wholly lost. The limbs are short, and the head is rather round. Males have more slender bodies than females. The neck and the tail are thick. The collar and other scales seem jagged.

The colour and patterning of this species is variable. The main colour is typically medium brown, but it can be also grey, olive brown or black. Females may have dark stripes on their flanks and down the middle of their backs. Sometimes females also have light-coloured stripes, or dark and light spots along the sides of their backs. Most males and some females have dark spots in their undersides. Males have brightly coloured undersides – typically yellow or orange, but more rarely red. Females have paler, whitish underparts. The throat is white, sometimes blue.

Range

The viviparous lizard is widely distributed throughout Europe and Asia. Its range extends to the north of the Arctic Circle. It ranges from Ireland to Hokkaidō and Sakhalin. It is absent from most of the Mediterranean area, although it occurs in northern Spain, northern Italy, Serbia, Republic of Macedonia and Bulgaria. It is also absent from the area surrounding the Black Sea.

Melanistic specimen are quite typical for the Großer Feldberg/Taunus mountain in Germany

Female

In the southern parts of its distribution range, the species lives at high elevations, occurring as high as 3,000 metres (9,800 ft) above sea level in the Alps. In these areas, the viviparous lizard lives in damp places or near water, including meadows, swamps, rice fields, by brooks and in damp forests. In the northern part of the range, the species is also found in lowlands, where it occurs in drier environments, including open woodland, meadows, moorland, heathland, fens, dunes, rocks, roadsides, hedgerows and gardens. It lives mainly on the ground, although it may climb onto rocks, logs and low-growing vegetation.

Behaviour

The viviparous lizard feeds on invertebrates, mostly small insects. It shakes larger prey in its jaws before chewing it and swallowing it whole. In early spring, late autumn, and cool summer days, it basks in the sun to reach its optimum body temperature, which is about 30°C (86°F).

These lizards mate in April or May. Males take females in their jaws before mating – if the female is not interested, she will bite the male fiercely. The offspring develop for about three months inside the female.

The name of the species is derived from its ability to give birth to live young, an adaptation to a cool climate, but some southern populations are oviparous (egg-laying). The three to 10 young (or eggs) are usually produced in July. The blackish young measure about 3 cm (1.2 in), and when first born are surrounded by egg membrane, from which they break free after about a day. Males reach sexual maturity at two years old, females at three years old. Individuals from viviparous and oviparous populations may be hybridised, but with significant embryonic malformation.^[4] Viviparous Z. vivipara do develop placentae to facilitate pregnancy but there is no substantial transport of nutrients as seen in some other species of viviparous reptiles (e.g. Pseudemoia entrecasteauxii).

In northern regions, viviparous lizards begin hibernation in September or October, underground or in log piles. Hibernation ends about mid-February. Further south, the species is active throughout the year.

Wikimedia Commons has media related to Zootoca vivipara.

Notes