Snakes are fascinating creatures. They slither along the ground on their bellies, "smelling" with their tongues. They do not have external ears. Since snakes cannot see or hear very well, they rely most on their sense of touch and smell. Some snakes have a special sense that helps them detect minute changes in temperature, which helps them locate warm-blooded animals. They have small pits between their eyes and nostrils that can detect a temperature change as small as 0.002 degrees Celsius.
You can find snakes almost anywhere in the world. One of the smallest snakes, the Carribean thread snake, has been recently discovered on the island of Barbados. This snake is only 3.9 inches long and, like the name suggests, its body is thin and "threadlike." At the other end of the spectrum, the 30-foot anaconda is found in the jungles of South America. Venomous snakes, such as the different types of rattlesnakes, are found in many locations.
There are over 2,700 types of snakes. The majority of snakes belong to one of five families of snakes. The largest family is the Colubridae family. Most of these snakes are harmless to humans and account for almost 2/3 of the world's snakes. The Elapidae family has very poisonous snakes, including cobras, coral snakes and taipans. Snakes that belong to the Boidae family are constrictors. Pythons and the anacondas belong to this family. The Viperadae family contains the most venomous snakes in the U.S., including rattlesnakes and vipers. Hydrophiidae snakes are sea snakes. These snakes are very poisonous.
Snakes come in all sizes, from the giant 30-foot anaconda to the Carribean thread snake that is so small that it's no wider than a noodle. The dusky pigmy rattlesnake is only about 1 1/2 feet long. The largest snake in the U.S. is the eastern diamondback rattlesnake, which can grow to be six-feet long. Although it has a rattle on its tail, it does not always make noise before it strikes.
Snakes are covered in scales, have no legs, eyelids or external ears. They can come in a variety of colors. Many of the venomous snakes have bright colors or rattles to warn predators. Some of them, such as the diamondback rattlesnake, have diamond -shaped patterns along its back.
Snakes have different features to help it use its senses. For instance, A snake has no outer ear, but it does have a small ear bone which is attached to its jaw that helps the snake detect very low sounds and vibrations. Another interesting way a snake uses its senses is the way it smells--or interprets odors. Instead of having nostrils to bring air particles in contact with the olfactory nerves to distinguish scents, a snake uses its tongue for this purpose. A snake flicks its forked tongue into the air to pick up air particles. The snake then brings those particles in contact with its Jacobson's organ, which is located on the roof of the snake's mouth, by inserting the tip of its tongue into two ducts. This is why the snakes tongue is forked, so that it can insert it into both ducts at once. This organ can then detect if the smell is that of a predator, prey or something else. The Jacobson's organ can also sense pheromones, which are the chemicals emitted by another animal of the same species. Pheromones are usually emitted as a warning, or to find a mate.