SELF-IMPROVED EYESIGHT
To give their eyes the best chance at spotting not only prey but potential predatory threats, some species of snakes have a handy trick to clear up their vision. Species such as the coachwhip (Masticophis flagellum) have evolved a way to control the blood flow to their eyes. While in a resting state, these snakes regularly cycle through the contraction and relaxation of blood vessels in the transparent layer of skin that covers the eye, called the spectacle. This helps prevent blood pooling around the eye, which is already limited in its vision. When the snake is threatened or under attack, these blood vessels are constricted, reducing blood flow and providing the best visual clarity possible so that the snake can defend itself or flee the scene.