Blue Whales Giant Mammals

Blue Whales. Giant Mammals. Written by S .E. Virgilio. Focus Question. What features allow the blue whale, a mammal, to survive in water?

蓝鲸。 巨型哺乳动物。 S·E·维吉里奥 著。 探究问题。 蓝鲸作为哺乳动物，有什么特征能让它在水中生存呢？

Introduction Far out at sea, scientists scan the horizon. They are looking for the largest creature on Earth. You would think that finding an enormous animal would be easy, but oceans are vast and wide. Suddenly, a thunderous roar sounds as a blast of water shoots high into the air. The scientists have found what they were looking for. The mighty, magnificent blue whale.

引言 在远海之上，科学家们眺望着海平面。 他们在寻找地球上体型最大的动物。 你肯定觉得找到这么大的动物很容易，但海洋实在太过辽阔。 突然，一声雷鸣般的轰响传来，一股水柱喷向高空。 科学家们终于找到了他们搜寻的目标。 那就是强大壮美的蓝鲸。

A blue whale's size is impressive. It can weigh as much as 200 tons, 181 .4 metric tons, and be as long as approximately 100 feet, 30 .5 meters. Its tongue alone weighs as much as an elephant. Its heart is so large that a person could crawl through its main blood vessels.

蓝鲸的体型令人惊叹。 它最重可达200吨（181.4公吨），最长约100英尺（30.5米）。 光是它的舌头就和一头大象一样重。 它的心脏大到一个人可以钻过它的主血管。

The blue whale has a mammoth body. Its skin actually looks blue underwater, but from above it looks blue -gray. The underside of a blue whale sometimes appears to be pale yellow thanks to tiny organisms called diatoms that often hitch rides on the whale's skin.

蓝鲸拥有庞大的身躯。 在水下它的皮肤看起来是蓝色的，从海面上方看则是蓝灰色。 蓝鲸的腹部有时呈淡黄色，这是因为一种叫硅藻的微小生物常附着在它的皮肤上。

Blowholes and Blubber Blue whales live in the sea, but they are not fish. These graceful giants are the world's largest mammals. Blue whales have lungs and breathe air just like humans. They inhale and exhale through two blowholes on top of their heads. In order to breathe, a whale must come to the ocean's surface. The blowholes open and the whale expels air, sending water spouts up to 30 feet, 9 .1 meters into the sky. Then the whale quickly inhales, filling its massive lungs. All of this happens in under two seconds.

喷气孔与鲸脂 蓝鲸生活在大海里，但它们不是鱼。 这些优雅的巨兽是全世界体型最大的哺乳动物。 蓝鲸和人类一样，长着肺，呼吸空气。 它们依靠头顶的两个喷气孔吸气和呼气。 为了呼吸，蓝鲸必须游到海面上来。 喷气孔打开后，蓝鲸排出废气，将水柱喷到30英尺，也就是9 .1米高的空中。 接着蓝鲸快速吸气，填满它巨大的肺。 这整套动作不到两秒就能完成。

A whale breathes in and out several times at the surface before beginning a dive. It uses its flexible spine and wide tail flukes to navigate through the water. Flukes are made up of tissue, not bone, so they are flexible. Blue whales leave circles called fluke prints on the water's surface when they dive. These whales usually cruise along at 5 miles per hour, 8 kilometers per hour, but they can travel as fast as 20 miles per hour, 32 kilometers per hour. Blue whales can stay underwater for about 30 minutes. They are considered shallow divers because they rarely go deeper than 700 feet, 213 .4 meters. In contrast, sperm whales dive about 3 ,280 feet, 1000 meters, more than four times deeper.

蓝鲸下潜前，会在海面呼吸好几次。 它依靠灵活的脊柱和宽大的尾叶在水中行进。 尾叶由软组织构成，不是骨头，所以十分灵活。 蓝鲸下潜时会在海面留下叫尾叶痕的圆形水纹。 蓝鲸通常每小时游5英里（8公里），但最快能达到每小时20英里（32公里）。 蓝鲸可以在水下停留大约30分钟。 它们属于浅潜动物，因为很少潜到700英尺（213.4米）以下。 相比之下，抹香鲸能潜到3280英尺（1000米），深度是蓝鲸的四倍多。