Estivation: The summer’s urge to nap

October 17, 2023 11:06 am | Updated 11:22 am IST

Aestivation  is to endure hot conditions while animals like this hedgehog hibernate to survive the winter.

Aestivation is to endure hot conditions while animals like this hedgehog hibernate to survive the winter.

Ever felt the urge to sleep through a hot day? Some animals do exactly that to beat the heat, but for a whole season. This is called estivation (or aestivation). It is a biological phenomenon whereby the animal enters a long period of dormancy, or inactivity, in response to high temperature or maybe even drought-like conditions. It is a survival strategy that helps the animal conserve energy and water in a difficult time.

During estivation, the animal often seeks shelter in a cool underground burrow, crevice or cocoon, where it will remain in a state of reduced metabolic activity, which in turn reduces the rate at which the body consumes energy. Estivation can also be a way to avoid desiccation – i.e. extreme dryness of the skin – and also lower the risk of being preyed on by a predator.

For example, the West African lungfish (Protopterus annectens) burrows into the mud of a drying water body and secretes a cocoon of mucus around itself during a drought. Desert tortoises (Gopherus agassizii) dig burrows and retreat into them in hot summer months. Many land snails seal themselves in their shells with a mucous plug, and stay inactive until the conditions outside improve.

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