Many people know that marine mammals, like whales, porpoises and dolphins, breathe air, like we do. But, many people don’t know that marine mammals have developed some interesting sleeping habits in order to accommodate their regular trips up to the surface for air. Today, A Moment of Science looks at what its like to sleep with the fishes.
No Sleep Tonight
Unlike our own breathing, which does not require conscious effort, marine mammals must consciously go to the surface of the water to breathe through a blowhole on top of their heads. Because of this, marine mammals don’t sleep for a solid 8 hours a night, the way we do.
Some marine mammals sleep while swimming. Whales nap for brief periods while swimming alongside an alert friend who guides them. In fact, young whales must sleep alongside their mother because the mother’s slipstream actually pulls the calf along: it will sink if the mother stops.
Dolphin
Other marine mammals, like dolphins, sleep while floating on the surface of the water or take short catnaps while floating below the surface. Researchers claim that while marine mammals sleep their brain is always partially alert. Aside from these brief naps, dolphins are active most of the night.
Of course, marine mammals are equipped to handle underwater sleeping. They have proportionately larger lungs, exchange air more fully at each breath, and carry more oxygen in their blood than we do, so they can hold their breath long enough to sleep with the fishes.
【英语听力文章：海洋生物有趣的睡觉习惯】相关文章：
小学三年级英语上册期中模拟练习卷02-07
冬至作文300字02-07
我找到春天了作文400字02-07
家乡的植物园02-07
山西省考面试流程是怎么样的02-07
餐饮员工辞职信经典范文02-07
2016课前三分钟英语演讲稿范文02-07
60字简单英语作文带翻译：我的习惯02-07
外婆作文400字02-07