Nile crocodiles resting at entrance to aestivation cave during the dry season | Pic by: Shah Rogers | Source:

Have you ever heard of a spell that can calm you down, and make you tired enough to sleep; a famous witchcraft? In the world of wilderness, it’s not witchcraft, but an intrinsic natural phenomena, driven by seasonal changes. In major, winter and summer are responsible for this.

The winter sleep is called ‘hibernation’, while the summer sleep is named as ‘Aestivation.’ Even though both hibernation and aestivation looks similar, there are many differences and different kinds of animals undergo with those both kinds.

The winter sleep
As the weather gets colder you might find it hard to wake up in the morning, but don’t worry you aren’t the only one. In fact, there are some animals that, no matter how loud their parents may yell, don’t get up at all, choosing instead to stay asleep all winter! They hibernate or go into a deep sleep as an adaptation to the cold months of winter. Hibernation is different from normal sleep. During hibernation an animal seems to be dead.

Its metabolism slows down and its body temperature drops. Its heartbeat slows to only two or three beats a minute. Since its bodily processes are so slow, it needs very little food to stay alive.
Before entering hibernation, animals need to store enough energy to last through the entire winter. Larger species abnormally increased their appetite for consumption of food to eat a large amount of food and store the energy in fat deposits. In many small species, food caching replaces eating and becoming fat.

The most famous hibernators are bears’, even though they aren’t real hibernators in the sense. These furry mammals don’t hibernate in the true sense because their body temperature only drops a little bit and they can wake up at any moment. In fact, a pregnant mama bear will have her cubs during the hibernation period. Like true hibernators, the bear’s heartbeat will slow down and they can go for a long time without having any food.

Hibernating box turtles are found in well hidden spots around America. The length of their winter sleep depends on the location and turtle subspecies: some can last as short as 77 days or as long as 154 days. Their heart beat drops to just one every 5-10 minutes and they don’t have to breathe in air at all. They are still very sensitive to the changing environment around them; if they wake up too early they will likely not survive. Unlike the others, who hibernate alone, garter snakes hibernate in groups.

In Canada, where winters are exceptionally cold, there can be hundreds and sometime thousands of snakes grouped together for warmth. Once spring arrives and the snow melts, they head out of their winter homes to bask in the sun.

Summer dreaming
Aestivation is a rare type of dormancy similar to hibernation, but it occurs during the summer. Animals that aestivate spend a summer inactive and insulated against heat to avoid the potentially harmful effects of the increase in temperature and lack of water or to avoid contact with other species with which they may otherwise be in competition, or for which they are prey. Both land and aquatic animals undergo aestivation.

Animals that aestivate include salamanders, desert tortoises, crocodiles, and lungfishes. Lady beetles, some crabs and mosquitoes also are reported to undergo aestivation. The lungfish aestivates by burying itself in mud formed at the surface of a dried up lake. In this state, it can survive for many years. Other animals aestivate in their burrow and wait for autumn to come.

Some animals, including the California red-legged frog, may aestivate to conserve energy when their food and water supply is low. Snails also aestivate during periods of heat during the day. They move into the vegetation, away from the ground heat, and secrete a membrane made of calcium over the opening to their shell in order to prevent water loss.

’Heating together' Garter snakes |  Source :
’Heating together’ Garter snakes |
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The lungfish who aestivates by burying itself in mud | Source :
The lungfish who aestivates by burying itself in mud | Source :
Garden Snails aestivating in a sheltered alcove beneath a log | Source:
Garden Snails aestivating in a sheltered alcove beneath a log | Source:
A black bear in deep sleep  | Source :
A black bear in deep sleep | Source :
Hibernating box turtle |  Source :
Hibernating box turtle |
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