wwrite short notes
1Hibernation
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Answer:
Hibernation is a way for many creatures – from butterflies to bats – to survive cold, dark winters without having to forage for food or migrate to somewhere warmer. Instead, they turn down their metabolisms to save energy.
Animals in hot climates also undergo a form of hibernation called aestivation. This works in a similar way and enables them to survive extreme heat, drought or lack of food.
Hibernating is much more profound than simply sleeping, though. Depending on the species, it can vary from long, deep unconsciousness to light spells of inactivity.
But hibernation carries risks as the dormant animal is vulnerable to predators and the unpredictable climate.
Which animals hibernate? Small mammals, such as chipmunks, dormice, hamsters, hedgehogs and bats. Also, many insects, amphibians and reptiles.
How does it work? A hibernating animal’s metabolism slows and its temperature plunges – in ground squirrels it can fall to -2°C. Breathing slows and, in bats, the heart rate can fall from 400 to 11 beats per minute. Some cold-blooded animals, such as wood frogs, produce natural antifreezes to survive being frozen solid.
How do they prepare? Mammals feed heavily in summer and autumn, storing fat to see them through the winter.
What are the dangers? Animals may die during hibernation from lack of fat, severe weather or premature awakening.
Hibernation is a state of minimal activity and metabolic depression. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most commonly occurs during winter months.