snake, (suborder Serpentes), also called serpent, any of more than 3,400 species of reptiles distinguished by their limbless condition and greatly elongated body and tail. Classified with lizards in the order Squamata, snakes represent a lizard that, over the course of evolution, has undergone structural reduction, simplification, and loss as well as specialization. All snakes lack external limbs, but not all legless reptiles are snakes. Certain burrowing lizards may have only front or hind limbs or be completely legless. Unlike lizards, snakes lack movable eyelids, which results in a continuous and often disconcerting stare. Snakes also lack external ear openings. Internally, they have lost the urinary bladder. The visceral organs are elongated, with reduction of the left member in relation to the right; the left lung is greatly reduced or even lost entirely. However, snakes possess increased numbers of vertebrae and have developed two novelties among vertebrates: a tracheal lung in the neck region and a venom-conducting system for subduing prey.
THEY CAN SMELL WITH THEIR TONGUES.
A snake uses its tongue to help it smell. It flicks its long, forked tongue to pick up chemical molecules from the air, ground, or water. The tongue carries the smelly molecules back to two small openings in the roof of the snake's mouth where they're analyzed.
THEY CAN "SEE" HEAT.
Some snakes—such as pythons, rattlesnakes, and copperheads—can't see well and use other senses to find prey. These creatures have openings called pit holes in front of their eyes. These pits sense the heat given off by warm-blooded prey. The snakes' heat vision allows the vipers to track prey day or night.
THEIR VENOM CAN KILL AND CURE.
By sinking two hollow, pointy fangs into their prey, many snakes inject venom to paralyze or kill victims before devouring them. But scientists have also discovered that the same poison that causes awful symptoms—and even death—in people who have been bitten by a venomous snake can be turned into medicines.
SOME SPECIES CAN FLY.
Flying snakes flatten their ribs into a concave C shape to trap air under their bodies as they fall. By undulating back and forth in an S-shape, they can actually glide through the air.
THEY CAN CHANGE THEIR SKIN.
Snakes literally grow out of their skin. Every few months, most start rubbing against the ground or tree branches. Starting at the mouth, a snake slithers out of its too-tight skin. Like a sock, the skin comes off inside out. Voilà—the snake has a fresh, shiny look. Nice makeover.
THEY "HEAR" WITH THEIR JAW.
Snakes don't have external ears to hear sound waves in the air. Instead, bones in their lower jaw pick up vibrations in the ground or water. The vibes trigger signals in the snakes' brains, which are received as messages. "Juicy mouse coming closer!"
THERE ARE A LOT TO LOVE
More than 3000 species of snakes slither around the world.
THEY ARE SPEEDY.
The black mamba snake slithers up to 7 miles per hour (11 kilometers per hour)!
Snakes can control the amount of venom they inject and may bite aggressively for food or defensively for protection. Snakes have a limited amount of venom available at any given time and do not want to waste it on nonprey organisms. As a result, about 40 percent of bites suffered by humans are defensive in nature and “dry” (without envenomation). Statistics show that the vast majority of snakebites occur while either catching and handling captive snakes or trying to molest or kill wild ones. In either case, the snake is only defending itself. Rattlesnakes, for example, are venomous, and large ones are quite dangerous owing to the amount of venom they can inject. However, most are shy and retreating, and none will attack a person unmolested. When approached or molested, they will coil up and rattle as a warning to be left alone, striking only as a last resort. Most cases of reputed snake attack are based upon encroachment by a person into the snake’s territory, which makes it feel trapped or cornered, or provocation of a snake during the breeding season. Even in these scenarios, only two snakes have a reputation as dangerous aggressors: the black mamba (Dendroaspis polylepis) of Africa and the king cobra (Ophiophagus hannah) of Southeast Asia. Nevertheless, snakes are inoffensive under the vast majority of circumstances. People are rarely indifferent about them, generally exhibiting emotions that range from religious awe and superstitious dread to repulsion and uncontrollable fear.
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