L3　動物睡覺跟你我一樣嗎？

Many animals have interesting sleeping habits. ___(27)___, giraffes sleep as little as 30 minutes a day! This is because dangerous animals may be nearby, and thus a giraffe could ___(28)___ if it sleeps for too long. Another example is the sea otter, surely one of the cutest animals around. While sleeping, sea otters make a charming sight; they ___(29)___ around on water on their backs and hold each other's hands tightly. This prevents them from getting lost while sleeping. As for dolphins, these animals are only ever half asleep. Because dolphins need to perform important tasks regularly, such as swimming to the top of the water for air, only half of their brains sleeps at one time. That way, the other half is able to keep ___(30)___. Besides these three, there are surely many others among the world's animals that have funny or cute sleeping habits. These examples show how each animal sleeps in a way that helps it ___(31)___ in its particular environment.

Are you ready for some wild and wonderful facts about animal sleep? Did you know that giraffes sleep for only about thirty minutes a day ___(22)___ average? When they sleep, they ___(23)___ their heads on their hips. ___(24)___, they can't stand up from this position quickly, so they don't sleep for very long. By contrast, sea otters ___(25)___ for their adorable sleeping position. They ___(26)___ on their backs in the water. Dolphins also have a unique sleeping habit: only half of their brain sleeps ___(27)___ a time. This enables them to swim to the surface to ___(28)___ every twenty minutes. Finally, Alpine swifts sleep in the air and can keep ___(29)___ for up to two hundred days.

Dr. Claire Mason is an expert in animal sleep behavior. In her book, While They're Sleeping!, she explores the strange yet wonderful ways animals get their rest. The first chapters explore ___(23)___ animals protect themselves while sleeping. For example, giraffes, who sleep for only thirty minutes a day to avoid predators, ___(24)___ first. The unusual way sea otters sleep is also mentioned. After that, the incredible sleeping habits of Alpine swifts and dolphins are explained. ___(25)___ half of the book mainly explains hibernation in bears and other animals. It focuses on how they survive without food for months and where they rest ___(26)___ this time. Dr. Mason also discusses how these animals prepare to hibernate for such long periods. ___(27)___, this book is one of the best resources on the subject. Get your copy today!

Sleep is a very important part of life for many animals. Most animals, like humans, need to rest well to recharge their bodies and stay healthy. Some animals, ___(32)___, have very special sleeping habits. For example, most giraffes spend only 30 minutes a day sleeping. This allows them to keep an eye on dangerous predators. Also, dolphins are able to "turn off" half of their brain ___(33)___ they are sleeping. That is, when one half of their brain is asleep, ___(34)___ half stays awake. This helps them stay sharp and swim to the top of the water for air. You might also be surprised by ___(35)___ migratory birds sleep during their long migrations. ___(36)___ studies, some migratory birds sleep up in the sky when they travel. By doing so, they can stay away from wild animals on the ground and also travel ___(37)___ farther. As you can see, some animals sleep in ways that we can only dream of.

Humans usually sleep for several hours each night. Animals, however, have developed ___(27)___ sleeping habits. Some animals sleep little, while others can sleep in unusual places or even while they are active. Unlike most mammals, giraffes take very short naps. ___(28)___, they often sleep for only half an hour a day. When they do sleep, they curl their necks and rest their heads on their hips. This is because they need to be able to stand up quickly to avoid ___(29)___ predators. Sea otters have one of the cutest ways of sleeping. They float on their backs in groups and ___(30)___ each other by locking their paws together. This helps them stay safe in the water and prevents them from drifting away. Dolphins have a very interesting sleeping habit. It is common for them ___(31)___ with only one half of their brain at a time. This allows them to swim toward the water top to breathe while ___(32)___ half of their brain rests. Some migratory birds, like Alpine swifts, even sleep while ___(33)___. They stay in the air for long periods of time ___(34)___ landing to stay away from wild animals on the ground. As you can see, different animals have different ways of sleeping to keep themselves safe and away from danger. Clearly, every animal is a(n) ___(35)___ expert in the wild.

You may know that brown bears hibernate and ___25___ goldfish sleep without closing their eyes. You might be surprised when you read the following amazing facts about animals' sleeping habits. ___26___ most mammals, giraffes sleep very little. In fact, it ___27___ that some giraffes sleep only thirty minutes a day. Sea otters float on their back and hold hands while they are sleeping. They can rest on the land, but they are ___28___ safer in the water. ___29___ away, they lock their little paws together. When dolphins sleep, only half their brain is asleep at a time. When one half of their brain goes to sleep, ___30___ half stay awake to help them swim, breathe, and ___31___ on the lookout for danger. Some ___32___ birds sleep up in the sky! ___33___, Alpine swifts have to keep flying for a long time during their journeys ___34___ Africa. Along the way, they eat insects in the air and take little naps while ___35___ flight. ___36___ you can see, each animal is an expert.

In spring, bears, frogs, and many other animals wake up from hibernation—a state where they sleep through the winter. Hibernation is a survival strategy because, without it, many animals would freeze or starve. It is more than just sleeping; it involves important changes in the body. When bears hibernate in winter, their heart rates slow down from about 50 beats per minute to around 10. Their body temperature also drops by 7 to 8 degrees Celsius. Bears can lose up to 40 percent of their body weight during hibernation, which is why they eat a lot to store fat before their long sleep. Interestingly, bears do not go to the bathroom during this time; their bodies can use waste as protein. Wood frogs are the most extreme hibernators. Their hearts actually stop beating, and 65 percent of the water in their bodies freezes during winter. They can stay frozen for up to seven months. When the weather warms up, their frozen blood melts, their hearts start beating again, and they are ready to hop around like before. The weather can be harsh sometimes, but nature has many ways to protect animals. Hibernation is one of these ways.

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