It is somewhat similar to hibernation. The animals are inactive and have a lowered metabolic rate. The state is entered in response to high temperatures and dry conditions. Lungfish have been doing this since the Devonian period. It takes place during times of heat and dryness, the hot dry season, which is often but not necessarily the summer months. A wide range of animals aestivate, including the Nile crocodile and many snails and lady beetles.