Snakes exist on every continent except for Antarctica, which is inhospitable to all cold-blooded animals. The continent of Australia is home to many of the deadliest snakes in the world. However, the nearby island nation of New Zealand has no snakes at all. Scientists estimate that snakes originated about 100 million years ago when the continents were joined, and the snakes stayed on the main land masses of the continents when they split apart. There are no snakes in New Zealand because they are unable to swim and therefore could not make the journey.