In the lizards Ophisops elegans, which are active during the daylight hours, a black layer covers the body cavity to protect their internal organs from the harmful effects of the sun. This layer is absent in newly hatched lizards and develops later. This layer is also used to accumulate heat. This black veil does not form in the lizard Teniudactilus caspius, which is mainly active at nights. Population density of Ophisops elegans is not high in places with no vegetation. Vegetation also affects Ophisops elegans distribution. There is a relationship between this lizard and the presence of vegetation. In lizards exposed to stress, most of the blood is retained in various organs and the amount of circulating blood decreases sharply.