When does aestivation in animals take place?

Aestivation is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. It takes place during times of heat and dryness, the hot dry season, which are often the summer months.

Invertebrate and vertebrate animals are known to enter this state to avoid damage from high temperatures and the risk of desiccation. Both terrestrial and aquatic animals undergo aestivation. The fossil record suggests that aestivation may have evolved several hundred million years ago.

Organisms that aestivate appear to be in a fairly "light" state of dormancy, as their physiological state can be rapidly reversed and the organism can quickly return to a normal state.