Hibernation and Estivation
Some animals 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. Some animals which hibernate are toads, skunks, ground squirrels, bees, and bats. Bears sleep during the winter, but they are not true hibernators. They wake up when they hear loud noises. Some animals estivate, or go into a deep sleep as an adaptation to the hot, dry months of summer. During estivation, an animal’s heartbeat and breathing slow down. During estivation, an animal does not grow or move. It does not need to eat because it is not using much energy. Some animals burrow underground, where it is cooler, before they begin to estivate. Some animals which estivate are reptiles, bees, hedgehogs, frogs, toads, and earthworms.