Colour vision can be found in at least some snakes. Tropical versions would be more likely to have colour vision then desert relatives and their skin generally reflects this.Time of day also effects vision. Nocturnal and crepuscular snakes usually have vertical pupils. A tapetum may or may not be present. Diurnal species generally have rounded pupils although this is not always the case as many boids have vertical pupils and a diurnal existence. Exceptions to the rule.
Strange as it might sound, it is true. Ground vibrations are transmitted through the snakes body to the quadrate bone (the connection between the lower jaw and skull) where it later goes the middle ear bone (columella) and then to the inner ear.This means that a snake will always hear you coming before you even see it.
Snakes, like all other tetrapods, have two nostrils with which to breathe. Other than breathing though the nostrils don't do much else in the way of smell. Instead snakes have gone a different route, one taken by their lepidosaurian relatives a long time ago. Instead of using only their nose, snakes have adapted their tongue and sense of taste to capturing scent particles in the air and transforming it into olfactory information.While many lizards have this ability only some truly use it to it's full extent and even then none go to the extremes of snakes. They accomplish this with the help of the vomeronasal organ or Jacobson's organ as it is more commonly called. This organ located at the roof of the snake's mouth, takes in information gathered by the tongue and transforms it into smell, thus making all snakes limbless bloodhounds with scales.
So it is no surprise to hear that snake bodies are flooded with tactile receptors that allow them to feel the slightest change in their environment. This allows for quick changes in muscular movement during locomotion as the snake's tactile receptors sense the slightest shift in the ground.Tactile receptors also come in handy during social encounters where touch and smell become the communication of choice. Snakes are very responsive to touch.
The two main groups of snakes have heat sensitive pits. The boids (pythons and boas) and the pit vipers (CROTALIDAE). Although a few other snakes possess this remarkable heat seeking ability, these two are the most prominent.In boids a row of heat pits are located on the lips in crevices called supralabial pits (top jaw) and/or infralabial pits (bottom jaw). These pits are able to sense slight changes in the ambient temperature, a valuable hunting tool for a nocturnal hunter.
The heat seeing ability of the pits allows pit vipers to hunt their prey in the complete darkness of a moonless night or in the hole of the prey. These pits are so sensitive that a blinded pit viper can sense a mouse that is a mere 100 warmer than the surrounding air from 70cm away. With such a powerful (almost science fiction like) ability it was quickly accepted that these crotalines used their pits for hunting. While this is no doubt true other findings have shown that the pits might serve another function entirely, for that of defense (As mentioned in Snakes: The Evolution of Mystery in Nature, by Harry W. Greene, p. 254-255). It is believed that with the increased parental attention crotalids showed towards their young combined with their rather static defenses, the pits would have been used to help evaluate and track potential threats in their environment.The chances are quite likely that the pits in crotalids were used for all of the above. Nature rarely gives something only one use.
With senses that range from ordinary (sight) to extraordinary (The Predator like heat seeing) is it a wonder why snakes have come to dominate so many terrestrial habitats?