Tarantulas occur worldwide . Those found in North America occur in the southern and southwestern states, including the dry and warmer parts of the southern California. These are smaller and generally have a body length of less than 2 inches and a leg span of from 3 to 4 inches.

There are over 850 different species around the world.

Tarantulas are members of the spider family Theraphosidae (order Araneida). They have hairy body and legs and come in wide color variation, from a soft tan, through reddish brown to dark brown or black.

A conspicuous bald spot seen on the abdomen of many tarantulas results from the spider's defensive behavior against its vertebrate enemies. When confronted, the spider will rub its hind legs over its body, brushing off irritating hairs into an enemy's eyes. These hairs are replaced during each successive molt.

The cephalothorax and abdomen Tarantulas, the front and rear parts of the body, are round. Their 8 eyes are closely grouped, with a pair in the middle and 3 on each side of the face. They have large fangs 2 pairs of slits on the underside of the abdomen that lead to the respiratory organs called book lungs. Book lungs have many folds lying close together like the pages of a book through which blood passes to acquire oxygen from the outside air.