Lizards have a wide range of defence mechanisms. Only two lizards are venomous - the beaded lizard and the Gila monster - and use their venom for defence. Many species of large lizards, although not venomous, can defend themselves against attack by biting vigorously.
When cornered, the horned lizard can spray an intruder with blood from the corners of its eyes or, like the chuckwalla, may retreat to a crevice and inflate its lungs with air, increasing its size so much that it cannot be pulled out of the narrow space.
The alligator lizard has protective, armour-like scales, while the agile swift darts behind the rocks or among the fallen trees of its habitat. Many lizards are cryptically coloured allowing them to camouflage around their surrounding environment. Some lizards, such as the chameleon, can change their colours as the external environment changes.