All snakes are carnivorous and use different methods for catching their prey. Venomous snakes use venom to cause paralysis, while nonvenomous species constrict, wrapping their bodies around animals and tightening until their prey suffocates. Several nonvenomous and venomous snakes have strong resemblances such as the milk snake and eastern coral snake.
The largest snake family in the world belongs to the Colubrids. This snake family accounts for nearly 2,000 of Earth's snake species. One defining characteristic of Colubrids is the head, which is usually not larger than the rest of their body. Also, Colubrids have round-shaped pupils. These slender snakes live in a variety of habitats, including forests, wetlands and underground. Even though most Colubrids are nonvenomous, a few species -- such as the boomslang and twig snakes -- have small fangs with venom. Neither one of these species are native to North America.
Boas and Pythons
Boas and pythons are two families of nonvenomous snakes with some similarities. Both families have long supratemporal bones, which are bones on the back of the snakes' skulls. These snakes rely on constriction to choke their prey. Also, boas and pythons have tiny, barely visible limbs near the snake's tail; these limbs resemble small claws. One of the primary differences between these two families, though, is pythons are oviparous -- laying eggs for reproduction -- while boas give live birth. Boas and pythons are nonvenomous and rely on constriction for subduing prey. One of the longest snakes in the world, the reticulated python, grows between 30 to 33 feet in the wild.
Burrowing snakes are nonvenomous, fossorial species that spend the majority of their lives underground. These snakes are able to create their own underground tunnels. Among the world's burrowing snake species are sunbeam snakes, pipe snakes and Asian pipe snakes. Burrowing snakes use their underground tunnels for finding food and laying eggs. Some burrowing snakes belong to the Scolecophidia infraorder of blind snakes. These snakes have vestigial eyes, or eyes with no useful function. Many blind snakes are mistaken for earthworms, due to their slender shape and short length.
Venomous snakes are species that use venom-induced fangs to paralyze their prey before eating them. Vipers are venomous snakes with long, hollow fangs at the front of their mouths. Also, most vipers -- rattlesnakes, cottonmouths, copperheads -- have facial pits between their eyes and nose; these pits have heat sensors that help them find warm-blooded prey in the dark. Elapids, such as cobras, corals and sea snakes, possess fangs near the rear of their upper jaw. The venomous snake group with the least amount of venom are burrowing asps; however, many of these snakes cause skin necrosis, or the premature deadening of skin tissue, with their bites.