The Frill-necked Lizard, or Frilled Lizard also known as the Frilled Dragon, (Chlamydosaurus kingii) is so called because of the large ruff of skin which usually lies folded back against its head and neck. The neck frill is supported by long spines of cartilage, and when the lizard is frightened, it gapes its mouth showing a bright pink or yellow lining, and the frill flares out, displaying bright orange and red scales. The frill may also aid in thermoregulation.
They may grow up to one metre in total length. They often walk quadrupedally when on the ground. When frightened they begin to run on all-fours and then accelerate onto the hind-legs. In Australia, the frill-necked lizard is also known as the "bicycle lizard" because of this behaviour. Males are significantly larger than females both as juveniles and when mature. The frill of the Australian frilled dragon is used to frighten off potential predators — as well as hissing and lunging. If this fails to ward off the threat, the lizard flees bipedally to a nearby tree where it climbs to the top and relies on camouflage to keep it hidden.