Thursday, 30 July 2009
A snake’s vision is mainly used for detecting movement of prey. They have difficulty seeing motionless prey or enemies. Objects probably appear as a blur at 40 feet, but at 10 to 15 feet, the objects appear sharper. The vision of many snakes, like the rattlesnake, is better suited for nocturnal searching. Some species, such as racers and garter snakes, have eyes specialized for daytime activity. Snakes appear to stare at their prey because they have no eyelids. The eyes of snakes are lidless, but are protected by a tough, transparent covering, or scale, that is shed with the skin. The pupil or the black portion of a rattlesnake’s eye is elliptical, not round as found with the nonvenomous snakes.