Instead, the tongue is used to bring smells and tastes into the mouth. Receptors in the pits then transmit smell and taste information to the brain. Snakes have no external ears. Instead, they are probably responding to the movements of the snake charmer and the flute. However, sound waves may travel through bones in their heads to the middle ear.
Snakes have no moveable eyelids.
Instead, they have a clear, scale-like membrane covering the eye. Sparrow Retina has 400,000 photoreceptors per sq. Spider Many spiders have eight eyes. Starfish Arms covered with light sensitive cells. Howard C. Hughes, Sensory Exotica.