There are about 2700 known species of snakes. The thread snake is known to be smallest of all snakes and anaconda the largest. They have scales which are outgrowths of skin all over their body. Snakes have all the senses that humans do. The brain and sensory organs are contained in the head. Snakes do not have a sense of taste but breathes smell into nasal openings. Snakes do not have any external or outer ears like us. In spite of having no organs that help them hear, how do they sense people moving around?
Snakes identify movements mainly due to vibrations from the ground or surrounding air. The part of the body that is in direct contact with the ground is quite sensitive to vibration. The skin, muscles and bones help carry the sound waves to the inner ears. The sound waves from the air hit their skin and are transferred from the muscles to the bones. The sound reaches the ear bone which is under the skull. These sound vibrations are sent to the inner ear and the brain processes these vibrations in the inner ear. Thus vibrations pass from the ground through their muscles to the bones and finally to the brain. This way they hear sound.
The organs of snake are arranged linearly because of their body shape. Snakes use their senses to hunt their prey, hide when there is a danger and also to find mate. They can also determine the size of the prey or danger by its movements. Their long moist tongue help pick up various smells. Though they do have teeth, they are known to gobble their food whole. Vision of snakes varies from species to species. While some can only differentiate light and dark, others have very keen eyesight.