Lizard heads called the parietal eye, a basal ("primitive") feature also present in the tuatara. This "eye" has only a rudimentary retina and lens and cannot form images, but is sensitive to changes in light and dark and can detect movement. This helps them detect predators stalking it from above. Until 2006 it was thought that among lizards, only the Gila monster and the Mexican beaded lizard were venomous. However, several species of monitor lizards, including the Komodo dragon, produce powerful venom in their oral glands. Lace monitor venom, for instance, causes swift loss of consciousness and extensive bleeding through its
Side-blotched lizard are now usually considered subspecies of "U. stansburiana". "U. encantadae", "U. lowei", and "U. tumidarostra" might be subspecies of a distinct species (Las Encantadas side-blotched lizard), instead. Similarly, "U. auriculata" and "U. clarionensis" might be subspecies of a single species, the Revillagigedo side-blotched lizard. Side-blotched lizard Side-blotched lizards are lizards of the genus Uta. They are some of the most abundant and commonly observed lizards in the deserts of western North America. Their cycle among three colorized breeding patterns has achieved notoriety and is best described in the common side-blotched lizard. They commonly grow to six inches including the tail,