There are almost 3,000 known species of snakes, and they live in almost every area of the planet except the coldest regions and Ireland and New Zealand. These reptiles also inhabit a wide variety of habitats, from oceans to deserts and plains to mountains. Three hundred seventy-five species are venomous.
Snakes vary widely in size, from the 4-inch-long Barbados thread snake to the 30-foot-long reticulated python. Weighing up to 550 pounds, the green anaconda is the world's heaviest snake. Snakes are cold-blooded, meaning that they must warm their bodies by utilizing heat sources from their external environments. Because of this, snakes in temperate regions often hibernate during the winter.
Depending on the species, snakes feed on birds, fish, eggs, small mammals and other snakes. The non-venomous king snake feeds on venomous snakes, such as rattlesnakes and water moccasins. Snakes hunt in part by flicking their tongues in and out, picking up scent particles that a special organ, called the Jacobson's organ, then reads. Venomous snakes kill their prey by inflicting a venomous bite, whereas constrictors suffocate their prey by squeezing. Snakes swallow their food whole, sometimes consuming creatures three times larger than their own heads. Most species of snakes lay eggs and leave the young to their own devices upon hatching.