There are 3,458 known species of snakes as of February 2014, according to The Reptile Database. This number changes periodically as new snakes are observed and some groups are reclassified.
A species is traditionally defined as a group of animals that are capable of reproducing with each other, bearing fertile offspring and sharing genetic information. In the contemporary scientific community, there is a shift to defining a species through evolutionary criteria. This leads to many animals, including snakes, being reclassified and creates disputes on which exact groups constitute a species. There are snake species on every continent except Antarctica. The islands of Ireland, Iceland and New Zealand are also free of snakes.