Snakes are elongated, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws.
To accommodate their narrow bodies, snakes´paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one fuctional lung. Some species retain a pelvic girdle with a pair of estigial claws on either side of the cloaca.
Living snakes are found on every continent except Antarctica, and on most smaller land masses - exceptions include some large islands, such as Ireland and New Zealand, and many small islands of the Atlantic and central Pacific. Additionally, sea snakes are widespread throughout the Indian and Pacific Oceans.
