The lovable (and lethal) sea lion - Claire Simeone

翻译人员: Carol Wang 校对人员: Liu Qi

Sunning themselves on rocks or waddling awkwardly across the beach,

岩石上晒着太阳 或海滩上蹒跚的海狮，

it’s easy to think of these immobile mammals less as sea lions,

这些不能正常行走的哺乳动物 容易让人觉得不像海狮，

and more as sea house cats.

而是像家猫。

But don’t be fooled by their beachside behavior.

但不要被它们在海滩上的行为所误导。

Under the waves, sea lions are incredible endurance hunters.

海浪之下，海狮是耐力超强的猎手，

Hurtling around at speeds from 4 to 18 miles an hour

它们时速可达4到18英里，

and hunting for up to 30 hours at a time,

一次狩猎可长达30个小时，

these majestic mammals live up to their name.

这些了不起的哺乳动物 绝对是实至名归。

And thanks to a suite of physical adaptations,

得益于一系列的身体适应变化，

finely tuned over millions of years, they make for resourceful foragers.

历经数百万年的细微调整， 它们成为足智多谋的觅食者。

To find their favorite food,

为找到最喜欢的食物，

sea lions hunt much deeper than many of their semi-aquatic peers.

海狮的水下捕食深度 远超许多半水栖同类。

With some species diving to depths of nearly 400 meters,

有些海狮种类可下潜到近400米，

they’re able to cope with the mounting pressure

面对不断增加的水下压力，

by collapsing their pliable rib cage, and compressing a pair of springy lungs.

它们收缩柔韧的肋骨、 压缩富有弹性的肺。

This pushes air up through the smaller airways,

使肺部空气上行通过狭窄呼吸道，

collapsing rings of cartilage as oxygen travels out from the lungs,

肺部氧气流出时， 软骨环同时收缩，

to be held in the larger, upper airways.

把空气封闭在更大的上呼吸道中。

Upon surfacing, this air will be used to re-inflate the lungs,

浮出水面时，这些空气 又会重新充满肺部，

but for now their heart slows down to preserve oxygen.

但现在，它们要减缓心跳来节省氧气。

Blood flow is redirected towards only the most essential organs

血液流向被改变， 仅流经最重要的器官，

like the heart, lungs, and brain,

如心脏，肺和大脑，

which rely on reserve oxygen stored in blood and muscle.

这些器官依赖于血液 和肌肉中储备的氧气。

Once they arrive at their hunting ground,

一旦抵达猎场，

sea lions depend on their superior vision to find their prey.

海狮凭借绝佳视力来发现猎物。

Most mammal eyes have a structure called a lens–

多数哺乳动物的眼睛 都有一种晶状体结构 ——

a transparent, convex structure whose shape refracts light to enable sight.

一种透明、凸起的结构， 可折射光线成像。

In humans, this lens is curved to process light waves traveling through air.

人类的晶状体是弧形的， 可以处理穿过空气的光波，

But sea lions need to see their best at hundreds of meters deep.

但海狮需要看清几百米深的地方。

To accommodate, their eyes have a much rounder lens to refract light underwater,

为了适应环境，它们拥有更圆的 晶状体来折射水下光线，

as well as teardrop-shaped pupils

同时还拥有泪珠状的瞳孔，

which can expand to 25 times their original size.

其瞳孔可以扩大25倍。

This lets in as much light as possible,

这可以使尽可能多的光线进入眼睛，

helping them pinpoint their prey in even the dimmest conditions.

帮它们在最昏暗的环境下 准确地找到猎物。

But once they’ve closed in,

但一旦它们接近了猎物，

they rely on something akin to a sixth sense to actually catch their meal.

它们依靠类似第六感来捕获食物。

Their whiskers, or vibrissae,

它们的胡须，或触须，

are composed of keratin and full of nerve fibers

由角蛋白组成，富含神经纤维，

that run deep into the connective tissue of their face.

神经纤维深入其脸部结缔组织。

Sea lions have full directional control over these whiskers,

海狮可全方位控制胡须，

which can lie flat against their face, or stick out at a 90-degree angle.

既可平贴脸上， 也能90度直直探出。

When properly tuned,

适当调整后，

these whiskers can sense the slim trails of moving water fish leave in their wake.

胡须能感知鱼儿游动留下的细小痕迹。

And they’re precise enough to let blindfolded sea lions

蒙眼的海狮可以通过胡须精确地区分

tell the difference between objects less than two centimeters different in size.

大小相差不到两厘米的物体。

With these tools a healthy sea lion can catch generous helpings of fish

借助这些工具，健康的海狮 每次外出时都能捕获大量鱼类，

such as anchovy, mackerel, and squid on every outing.

如凤尾鱼，鲭鱼和鱿鱼。

And with their exceptional memories, they can remember multiple hunting grounds,

凭借超凡记忆力， 它们能记住多个猎场，

including those they haven’t visited in decades.

包括几十年没去的猎场。

This memory also extends to breeding territories and birthing areas,

海狮也能记住繁殖和分娩区域，

as well as which neighbors are friend and foe.

以及那些邻居是敌是友。

There’s even evidence that sea lions can remember how to perform tasks

甚至有证据表明， 海狮还能记住如何在某地狩猎，

after 10 years with no practice in between,

即使10年没在那里狩猎，

letting them navigate old stomping grounds with ease.

这种超强记忆 令其轻松巡游旧地盘。

Yet despite these incredible adaptations,

然而，尽管有这些惊人的适应力，

there are changes unfolding in their habitats

栖息地的变化

too rapidly for sea lions to handle.

还是快得让海狮难以适应。

As climate change warms the oceans, certain toxic algae species thrive.

随着气候变化让海洋变暖， 某些有毒藻类繁荣生长。

This algae is harmless to the fish who eat it,

这种藻类对吃它的鱼无害，

but for the sea lions which ingest those fish,

但对于以这些鱼为食的海狮来说，

the algae’s domoic acid can trigger seizures and brain damage.

藻类的软骨藻酸 会引发癫痫和脑损伤。

Changing ocean conditions keep this algae blooming year round,

不断变化的海洋环境 使这种藻类终年繁盛，

causing more and more sea lions to wash up on beaches.

导致越来越多的海狮死亡， 被冲到海滩上。

This tragic discovery is just one of the many ways

这种悲剧的发现只是，

the health of aquatic animal communities can help us

我们通过水生动物健康状况，

来更好地了解地球海洋的方式之一。

better understand Earth’s oceans.

These red flags help us take action

这些红色警示帮助我们采取行动，

to protect ourselves and other maritime mammals.

去保护自己和其它海洋哺乳动物。

And the more we can learn about the changing ocean that sea lions inhabit,

越了解海狮栖息地海洋的变化，

the better equipped we’ll be to help these clever creatures thrive.

我们就能更好地帮助这些 聪明的动物繁衍壮大。