There are more than 37000 known species of spiders in the world in wide variety of shapes and size. The largest spiders in the world live in the rain forests of South America and are known by the people who live by there as the “ bird-eating” spiders. These spiders can grow up to 28 centimeters in length about the size of a dinner plate, and, as their name suggests, have been known to eat small birds. In comparison, the smallest species of spider in the world is native to Western Samoa. These tiny spiders are less than half a millimeter long about the size of period on this page and live in plants that grow on mountain rocks.