A few days ago a friend said ‘What with everything closed for Corona, it is so dull and boring, wish we could just HIBERNATE.’ Probably a sensible thought, except that given the temperatures outside, it would be aestivation, rather than hibernation.
AESTIVATION, lesser known cousin of hibernation, is ‘summer sleep’– a survival strategy used by many vertebrates and invertebrates to endure arid environmental conditions. Key features of aestivation, like hibernation (winter dormancy) include significant metabolic rate suppression, conservation of energy , altered nitrogen metabolism, and mechanisms to preserve and stabilize organs and cells over many weeks or months of dormancy. Even more than in hibernation, strategies to retain body water are important in aestivation, as dryness or aridity is the key trigger for the summer sleep.
A surprising number of animals aestivate—vertebrates such as lung fish, amphibians, reptiles, small mammals, and certain invertebrates such as molluscs. Bees, snails, earthworms, salamanders, frogs, earthworms, crocodiles, tortoise, etc. are examples of the aestivating animals. The duration of aestivation varies among species–some enter this state for a few months, others for a longer period.
Well, there are other kinds of ‘downtimes’ we can choose from too.
There is BRUMATION, which is the equivalent of hibernation for reptiles. Mammals hibernate and reptiles brumate, but there are other differences too. During hibernation, a mammal is sleeping and does not have to eat or drink. But brumation is not true sleep and the reptile still needs to drink water. A brumating reptile may have days where it will wake, show some activity, drink water, and then go back to its dormant state.
Or we can take the option of TORPOR, which involves lower body temperature, breathing rate, heart rate, and metabolic rate. But unlike hibernation, torpor is an involuntary state that an animal enters into as the conditions dictate. Also unlike hibernation, torpor lasts for short periods of time – sometimes just through the night or day depending upon the feeding pattern of the animal. During their active period of the day, these animals maintain a normal body temperature and physiological rates. But while they are inactive, they enter into a deeper sleep that allows them to conserve energy and survive the winter.
Or there is DIAPUASE, a form of developmental arrest in insects that is much like hibernation in higher animals. It enables insects and related arthropods to circumvent adverse seasons. Winter is most commonly avoided in colder areas, but diapause is also used to avoid hot, dry summers and periods of food shortage in the tropics.
Now, which one do you prefer?