Some Facts That May Surprise You about Sharks  一些有关鲨鱼的冷知识

Sharks are scary animals in the ocean， primarily for their big size and sharp teeth. Sharks have been around for hundreds of millions of years， and while they continue to evolve， they are also in grave danger. However， humans are a larger threat to sharks than sharks are to us. There are more than 500 species of shark. Given that there are a large number of unique species， some characteristics may be true for one species， but not another.

鲨鱼是海洋中令人闻风丧胆的动物，主要是因为它们巨大的体型和锋利的牙齿。鲨鱼已经存在了数亿年，在不断进化的同时，它们也处于极大的危险之中。但是，我们对鲨鱼的威胁远超过它们对我们的威胁。现存有500多种鲨鱼，但由于大量品种有其独特性，某些特征可能在一个品种身上有，在另一个品种身上就没有。

Sharks can live for hundreds of years.

鲨鱼可以活数百年。

Sharks have one of the longest life spans compared with other animals.

The Greenland shark is the longest-living known vertebrate on Earth， according to a 2016 study published in the journal Science. Researchers using radiocarbon dating determined that the North Atlantic species likely lives an average of at least 272 years， and often doesn’t reach maturity until 150 years of age. Greenland sharks can live for at least 400 years， scientists have estimated.

与其他动物相比，鲨鱼是寿命最长的动物之一。

《科学》杂志2016年发表的一项研究表明，格陵兰鲨是地球上已知最长寿的脊椎动物。研究人员利用放射性碳测年法确定，北大西洋品种的平均寿命可能至少为272岁，它们通常要到150岁才成年。科学家估计，格陵兰鲨的寿命至少可达400岁。

Sharks are older than trees and dinosaurs.

鲨鱼比树木和恐龙还要古老。

The earliest shark fossils date back as far as 450 million years， which means these creatures have been around at least 90 million years before trees and 190 million years before dinosaurs.

Sharks have been around since before Pangea broke apart， said Catherine Macdonald， lecturer at the University of Miami. Additionally， sharks have survived five mass extinctions， one of which wiped out around 96% of all marine life.

最早的鲨鱼化石可以追溯到4.5亿年前，这意味着这些生物的出现时间至少比树木早9000万年，比恐龙早1.9亿年。

迈阿密大学的讲师凯瑟琳·麦克唐纳说，鲨鱼在盘古大陆分裂之前就已经存在了。此外，鲨鱼曾经历过五次大规模的物种灭绝，其中一次约有96%的海洋生物灭绝。

Shark pregnancies can last longer than 3 years.

鲨鱼的孕期可以持续三年以上。

Reproduction patterns in sharks vary. On average， sharks give birth after 11 or 12 months of pregnancy， but some sharks， such as the frilled shark can be pregnant for over three years.

Some sharks， like bull sharks， give live birth， while other sharks， like cat sharks， lay eggs. Long pregnancy terms， and the fact that some sharks take 10 to 12 years to reach sexual maturity， like the great white， further impact populations.

鲨鱼的繁殖方式各不相同。平均而言，鲨鱼在怀孕十一二个月后分娩，但有些鲨鱼，如皱鳃鲨，可以怀孕3年以上之久。

一些鲨鱼，如灰牛鲨，是胎生；而其他鲨鱼，如猫鲨，是卵生。长孕期，以及一些鲨鱼（如大白鲨）需要10至12年才能达到性成熟的事实更深层次地影响其数量。

Sharks do not vocalize.

鲨鱼不会发声。

Sharks are primarily silent creatures， as they don’t have organs for producing sound. Instead of speaking， sharks communicate through body language， such as zigzagging， shaking and moving their jaws.

鲨鱼天生是沉默的生物，因为它们没有发声的器官。鲨鱼不发声，而是通过肢体语言进行交流，如游之字形、晃动下颌等。

Sharks can sense electricity.

鲨鱼可以感应电流。

Sharks have a sixth sense — they can pick up nanoscopic electromagnetic currents. This extra sense can help them navigate the ocean and find prey， or even a mate.

“The minute electrical impulse that a prey’s brain sends to its heart to tell it to beat can be sensed by sharks， so they can find hidden prey quite effectively，” Macdonald said. With this extraordinary sense， sharks hunt sick and weak animals， playing a crucial role in keeping the marine ecosystem healthy.

鲨鱼有第六感——它们可以感知纳米级的电磁电流。这种额外的感知可以帮助它们在海洋中找到方向和猎物，甚至是配偶。

麦克唐纳说：“鲨鱼可以感知到猎物大脑发送到心脏以使其跳动的微小电脉冲，因此它们可以非常有效地找到隐藏的猎物。”凭借这种敏锐的感知，鲨鱼捕食患病和虚弱的动物，在保持海洋生态系统平衡方面发挥着至关重要的作用。