The Smooth Newt (Lissotriton vulgaris), also known as the Common Newt, is the most common newt species in the Triturus genus of amphibians. It is found throughout Europe except the far north, areas of Southern France, and the Iberian peninsula. In Europe, newts are protected and it is illegal to sell, trade, kill or destroy them. While the smooth newt is not endangered, there is insufficient data to make an assessment for two of the subspecies. In the British Isles it is only illegal to sell such species. Killing or destroying them is not prohibited.
Outside of the breeding season, male and female newts are difficult to distinguish. Both sexes are similar in size (4 inches), and similar in coloration (pale-brown to yellow). One easy way to tell them apart is males have a single black line running down the center of the spine. Females have two parallel lines either side of the center. During the breeding season the male is clearly much darker than the female, with a tall wavy and transparent crest along the spine and tail, with dark spots covering the rest of the body , including the stomach area, which is a far more vivid pink or orange than it is in winter and autumn. The female also develops spots, but not on the stomach area, which is paler than the males, and theirs are generally smaller. The females do not develop crests. These newts have a paddle-like tail for increased swimming speed.
Adult Smooth Newts emerge from hibernation on land from late February to March, and head to fresh water to breed. They favor ponds and shallow lakesides over running water. During courtship the male newt “displays” for his prospective mate by vibrating his tail in front of the female in a distinctive fashion. The male then deposits a sperm-containing capsule, known as a spermatophore, in front of his mate, who maneuvers herself into a position whereby she can pick up the capsule with her cloacae – fertilization occurring inside the female. The female, thus fertilized, after a few days starts to lay eggs individually, usually under aquatic plant leaves at a rate of 7 to 12 eggs per day. Altogether a total of 400 eggs may be produced over the season.
After two to three weeks (depending on water temperature) the eggs hatch to a larval form – a tadpole. For a few days the tadpoles live off the food reserves contained within their yolk sacs (left over from the egg stage). After this they start to eat freshwater plankton, and later insect larvae, mollusks et cetera (unlike frog tadpoles, newts are carnivorous throughout their life). The newt tadpoles look initially like small fish fry, but later become more similar to miniature adults, but with “feathery” external gills emerging from behind the head on either side. As the tadpoles mature they develop legs (front first), and the growth and use of their lungs is matched by a gradual shrinkage of the gills. Thus the tadpole gradually shifts from being fully aquatic to possessing a body suitable for a mostly terrestrial existence, a tadpole typically leaving the water after ten weeks. Some tadpoles however may over-winter in the larval state, only emerging from the water the following year. Smooth newts take around three years to become sexually mature, on average living for six years.