Overview

Most snakes aren't dangerous to people. Only about 15% of snakes worldwide and 20% in the United States can inject poison when they bite. These snakes are called venomous. In North America, these include the rattlesnake, coral snake, water moccasin, also called cottonmouth, and copperhead. Their bites can cause serious injuries and sometimes death.

Most venomous snakes in North America have eyes like slits and are called pit vipers. Their heads are triangle-shaped and they have fangs. One exception is the coral snake, which has a cigar-shaped head and round pupils. Nonvenomous snakes typically have rounded heads, round pupils and no fangs.