Natricinae


The Natricinae are a subfamily of snakes in the family Colubridae. The subfamily comprises 37 genera. Members include many very common snake species, such as the European grass snakes, and the North American water snakes and garter snakes. Some Old World members of the subfamily are known as keelbacks, because their dorsal scales exhibit strong keeling.
Natricine snakes are found in Africa, Asia, Europe, North America, and Central America as far south as Costa Rica. A single species, Tropidonophis mairii, reaches Australia. Although the highest diversity is in North America, the oldest members are in Asia and Africa, suggesting an Old World origin for the group. Most species are semiaquatic and feed on fish and amphibians, although a few are semifossorial or leaf-litter snakes that feed on invertebrates. Most species are harmless to humans, but a few are capable of inflicting bites that can result in local, nonlife-threatening symptoms, and at least two members of the genus Rhabdophis are capable of inflicting life-threatening bites to humans, though they have only enlarged, ungrooved fangs in the back of the mouth.

Classification

While often regarded as a subfamily of the Colubridae, in some classifications, they are raised to the family level as Natricidae.
They are recognised as a sister group of the Dipsadinae plus the Pseudoxenodontinae.

Genera