WATER SNAKE

any member of the genus Natrix, family Colubridae, and similar snakes. The 65 to 80 species of Natrix occur on all continents except South America. Some authorities place the New World species in several genera, the largest of which is Nerodia. Most water snakes have dark blotches or dorsal streaks on their stout bodies, and the scales are keeled. They are semiaquatic, preying on fish and amphibians, which they kill with a nonvenomous bite. American forms are always found in or near water, and they bear 30 to 75 living young; European forms are less water-dependent, and they lay eggs. All members of the genus are notably bad-tempered; besides inflating the head and striking in self-defense, they release a foul secretion from the anal gland. In North America east of the Rockies, there are 11 species, typified by the widespread Natrix sipedon, the several races of which are given different common names. It is a blotched or banded brown snake about 90 centimetres (35 inches) long. It is often referred to as a moccasin because of its resemblance to the venomous, water-dwelling snake of that name. The common European water, or grass, snake (N., sometimes Tropidonotus, natrix) ranges from western Europe (including the British Isles) and North Africa to Central Asia. It is dark green to black, usually with small black dorsal spots, short bars on the sides, and a white, yellow, or orange mark on each side of the head or across the nape. Some specimens are nearly 1.8 metres (6 feet) long, but their average length is less than one metre. The checkered water snake (N. tesselata) of Europe to Central Asia is aquatic and a fish eater. The keelback (N. piscator) of India is named for its markedly keeled dorsal scales. The tiger grass snake (N. tigrina) of eastern Asia to Japan is mostly dark green or blue.