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
Northern alligator lizard coast and can be found from sea level up to elevation of about . It is found in a variety of forested habitats and montane chaparral. Northern alligator lizard The northern alligator lizard ("Elgaria coerulea") is a medium-sized lizard that occurs on the North American west coast. The northern alligator lizard was formerly known by the scientific name of "Gerrhonotus coeruleus" , but is nowadays assigned to the genus "Elgaria". Four subspecies are recognized as being valid, including the nominotypical subspecies: "Nota bene": A trinomial authority in parentheses indicates that the subspecies was originally described in a genus other than