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The whale is a warm-blooded, air-breathing animal, giving birth to its young alive, sucking them-and, like all mammals, originated on land. There are many {{U}}(51) {{/U}} of this. Its front flippers (鳍状肢), used for steering and stability, are traces of feet. Immense strength is {{U}}(52) {{/U}} into the great body of the big whales, and in fact most of a whale's body is one gigantic muscle. The blue whale's pulling strength has been estimated {{U}}(53) {{/U}} 400 horsepower. One specimen was reported to have towed (拖) a whaling vessel for seven hours at the {{U}}(54) {{/U}} of eight knots (节). An angry whale will {{U}}(55) {{/U}} a ship. A famous example of this was the fate of whaler Essex, {{U}}(56) {{/U}} was sunk off the coast of South America early in the last century. More recently, steel ships have {{U}}(57) {{/U}} their plates buckled (使弯曲) in the same way. Sperm whales (抹香鲸) were known to seize the old-time whaleboats in their jaws and crush them. The greatest {{U}}(58) {{/U}} of whales is their diving ability. The sperm whale dives to the bottom for his {{U}}(59) {{/U}} food, the octopus (章鱼). In that search he is known to go as far down as 3,200 feet, where the {{U}}(60) {{/U}} is 1,400 pounds, to a square inch. Doing so he will {{U}}(61) {{/U}} underwater long as one hour. Two special skills are involved in this: storing up enough {{U}}(62) {{/U}} (all whales are air-breathed) and tolerating the great change in pressure. Just how he does it scientists have not {{U}} (63) {{/U}}. It is believed that some of the oxygen is stored in a special {{U}}(64) {{/U}} of blood vessels, rather than just held in the lungs. And it is believed that a special kind of oil in his head is some sort of compensating mechanism that {{U}}(65) {{/U}} adjusts the internal pressure of his body. But since you can't bring a live whale into the laboratory, for study, no one knows just how these things work. |