Lizards
Lizards make up the largest group of reptiles with over 3000 known species and can be found on every continent other that Antarctica. They are very closely related to snakes and are grouped together. Most lizards have two pairs of legs, though there are some exceptions. Most lizards also posses movable eyelids and external ear openings. Lizards also tend to have similar sized scales over their entire body, unlike snakes.
Some lizards posses the ability to change colors. This is also know as metachrosis. The color changes according to light, temperature or mood. Chameleons have developed this ability to even allow them to blend into their surroundings. There are two species of lizard, the Mexican beaded lizard and the Gila monster, that are venomous.