Lizards are a widespread group of squamate reptiles, with more than 7,000 species. Lizards live on every continent except Antarctica and inhabit a wide range of environments; many groups are also widespread on islands. Many lizards are four-limbed and have movable eyelids and external ear openings, traits that usually help distinguish them from snakes. However, there are many exceptions: some lizards are legless, some have lost movable eyelids, and some lack external ear openings, so no single external feature identifies all lizards.
