The Greatest Mystery of Whales
The whale is a mammal-warm-blooded, air-breathing, giving birth to its young alive. ing them-and, like all mammals, originated on land. There are many signs of this. Its front flippers (鳍足), used for steering and stability, are traces of feet.
Immense strength is built 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 at 400 horsepower. One specimen was reported to have towed (牵引) a whaling vessel for seven hours at the rate of eight knots.
An enraged whale will attack a ship. A famous example of this was the fate of whaler Es, which was sunk off the coast South America early in the last century. More recently, steel ships have had their plates buckled in the same way. Sperm whales were known to seize the old-time whaleboats in their jaws and crush them.
The greatest mystery of whales is their diving ability. The sperm whale can dive on the bottom for his favorite food, the octopus. In that search he is known to go as far down as 3,200 feet, where the pressure is 1,400 pounds, to the square inch. Doing so he will remain submerged as long as one hour. Two feats(壮举) are involved in this: storing up enough oxygen (all whales are air-breathed) and withstanding the great change in pressure. Just how he does it scientists have not determined. It is believed that some of the oxygen is stored in a special system 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 automatically 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.
The Greatest Mystery of WhalesWhich of the following is a sign of the fact that the whale originated from the land