A snake has been on the earth for over 130 million years. Without limbs, it can climb, swim and sometimes fly. Some have a deadly bite that can kill a human. In religion, it was the animal that tempted Adam and Eve.
Of the 2700 known species, each share three common traits. It has a thin, linear limbless body, eats meat and is cold blooded. Its organs are linear in its body with the brain and sensory organs in the head. It has an inner ear which detects sound from sound waves hitting its skin. It cannot detect colors but can see images. Some have pit organs that can detect heat sources used for night hunting warm bloodied animals. It does not have a sense of taste but can smell odors. When it flicks its tongue, it gathers in air particles to assist in sensing odors.
It reaches lengths from 4 inches to 30 feet with hundreds of vertebrae making it very flexible. Its skin is elastic covered with scales. It will shed its skin many times during its lifetime. It reaches maturity from 1 to 9 years and can live from 4 years to over 25 years.
It moves using ventral scales on its underside which grip the ground and move it forward. It has four basic movements. Serpentine used by most snakes on land and water where it contracts its muscles into side by side curves and using its scales to propel forward. Sidewinding, a variation of the serpentine where it uses only two ground contact points. Caterpillar where the curves are up and down and above the ground. Concertina used for climbing, where the ventral scales grip the surface and it springs forward to regrip the surface.
It has an expandable jaw and can swallow prey larger than itself whole. It drenches its prey with saliva and crushes it with its muscles. Some snakes inject its prey with venom using its fangs to subdue it.
The venomous types which account for 20% of all snakes have 2 hollowed front teeth called fangs to allowed the poison to pass through. The venom contains one of three toxins. Neurotoxin which seizes the nerves centers and stops breathing. Cardiotoxin which attack the heart causing it to stop. Hemotoxin which causes blood vessels to rupture. Other snakes squeeze its prey by applying pressure of up to 12 pounds per square inch causing the lungs and heart to stop working.
It has been found in mythology and popular culture. It has been featured in books and movies. "Snakes on a Plane" and "Indiana Jones and the Raiders of the Lost Ark" have depicted it as an animal to fear. It also has been used as symbol of evil societies. In gardening and agriculture, it plays an important role in controlling insects.
