Like most animals on the planet, snakes have the five normal senses. Those would be sight, touch, smell, hearing and taste. Some features of the senses are limited, while others are extended beyond the norm.
Eyes - The range of sensitivity of the eyes vary greatly from snake to snake. Most snakes see the actual movement of objects clearer than the object itself. Snakes that are active during the day normally see in this fashion. On the other end of the spectrum, some snakes, such as the blind snakes, see shades of light and dark. Snakes do not have eyelids in the traditional sense. They cover their eyes with a clear membrane, called the brille.
Ears - Snakes lack an external ear opening. Their ear bone is attached to their jaw bone. They can only hear very low sounds.
Tongue - The snakes tongue is the most interesting part of their anatomy. Everyone knows the typical action for the tongue; flicking. Snakes flick out their tongue, and either wave it in the air, or touch the ground with it. This is one of their touch sensors. It is also used to find or detect chemical scents. Molecules of any chemical are collected by the tongue, brought back into their mouth, and analyzed by the Jacobson's organ. Using this method, a snake can more effectively find and follow its prey.
Some snakes can detect infrared heat rays. Some species of snakes have small holed, or pits, on their faces, including; pit vipers, boas, pythons. This pit allows them to distinguish minute changes in temperature in the direction they are pointed. Hunting prey is made simple by picking out warmer temperatures in front of them.