Aestivation Aestivation Aestivation or æstivation (from , summer, but also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, 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
Season of the Emergence known as Winter. In the lunar calendar, the intercalary month was added as needed to maintain the heliacal rising of Sirius in the fourth month of the season of the Harvest. This meant that the Season of the Emergence usually lasted from January to May. Because the precise timing of the flood varied, the months of "Emergence" no longer precisely reflected the state of the river but the season was usually the time for the planting and growth of Egyptian grain. In the civil calendar, the lack of leap years into the Ptolemaic and Roman periods meant the season lost