Snakebite (Snake Bite) Symptoms and First Aid Treatment: There are about 400 of 3,000 snake species worldwide are venomous. Approximately 25 species of venomous snakes are found in North America. Two major families of snakes account for most of the venomous snakes dangerous to humans. The elapid family includes cobras, mambas, coral snakes, tiger snakes, and death adders. The viper family includes rattlesnakes, saw-scaled vipers, Russell's viper, and the puff adder. If a person is bitten by a snake they should go to an emergency department, regardless if they feel the snake is nonvenomous.