As most people know, about 70 percent of the Earth's surface is covered in water. All said and done, there's about 1.3 billion cubic kilometers (332.5 million cubic miles) of water on the planet, and the seas and rivers and oceans that hold all that water are still some of the most poorly understood regions on Earth—and so are the creatures that live in them.
众所周知，地球表面70%都被水体覆盖。总而观之，地球上的水约有13亿立方千米（33250万立方英里），然而人们对盛着这些水的江河海洋却仍知之甚少——对生活在其中的生物也一样。
10.Colossal Squid Digest Food With Their Brains
10.巨型乌贼用大脑消化食物
The colossal squid, or Mesonychoteuthis hamiltoni, was believed to be a myth until recently, and we've still only seen a handful in real life. In 2007, the largest specimen yet was found and captured by a crew of New Zealand fishermen in the Ross Sea near Antarctica. It was massive—a full 10 meters (33 ft) long and almost 450 kilograms (1,000 lbs) in weight. The squid was hauled back to New Zealand to be studied, and they found something pretty incredible: Its digestive system runs right through the center of its brain.
巨型乌贼，即“大王酸浆乌贼”（Mesonychoteuthis hamiltoni），在世人眼中一直是个谜，直到最近才解开；然而我们实际上仍只看见寥寥可数的几只。2007年，最大的一只乌贼在南极洲附近的罗斯海出现，被几个新西兰渔民捉住。它体型巨大——整整10米（33英尺）长，几乎有450公斤（1000英镑）重。这只乌贼被运回新西兰进行研究，人们发现了一些不可思议的东西：它的消化系统贯通了大脑。
The brain is built like a doughnut—a ring of fleshy mass with a hole right in the middle. When the colossal squid swallows its prey, the esophagus carries it through the brain, which pulls nutrients directly from the food before it reaches its stomach. Gigantic squid like this inhabit the frigid waters of the deep ocean, and between the cold and their ridiculously slow metabolisms, they don't actually need much food to survive. In fact, the half-ton animal only needs 30 grams of food per day to survive. That's about what a single AA battery weighs.
它的大脑结构就像甜甜圈——一圈大脑组织，正中间一个洞。当巨型乌贼吞咽猎物时，食道把食物送到大脑，大脑从中直接吸收营养物质，然后食物才进入胃里。像这样巨大的乌贼住在深海冰冷的水中，在寒冷和极其缓慢的新陈代谢之间，它们实际不需要太多食物就能活下去。事实上，这种重达半吨的动物每天只需要30克（1盎司）食物。那大约就是一节5号电池的重量。
9.Piranha-Proof Fish Armor
9.防御水虎鱼的铠甲
Piranhas, the razor-toothed terrors of the Amazon River, have few natural predators and an almost endless buffet of potential prey. Although a single piranha might make a nice meal for a dolphin or a cormorant, their tendency to swim in schools of hundreds keeps most predators at bay, so piranhas live a largely lawless life. As a result, other Amazonian fish have had to adapt to their bullying neighbors, and even the largest fish in the Amazon—the Arapaima gigas or giant arapaima—needs a second layer of protection.
水虎鱼是亚马逊河里长着尖牙的恐怖分子。它们的天敌屈指可数，猎物倒是很多，几乎有吃不完的大餐。虽然单个水虎鱼可能成为海豚或鸬鹚口中的美餐，但是它们喜欢几百条一起成群结队出现的习性让大部分敌人敬而远之，因此，水虎鱼几乎过着无法无天的生活。最终，亚马逊河的其他鱼儿不得不适应这些粗暴的邻居，甚至亚马逊河里最大的鱼——巨骨舌鱼（Arapaima gigas）——都需要两层防护。
Giant arapaima are massive fish, weighing close to 130 kilograms (300 lbs) at adulthood. But as Teddy Roosevelt observed, a school of piranhas won't shy away from size alone, so the giant arapaima evolved armor to withstand the bites. Their scales are built in two layers—the outer layer is a hard, mineralized surface shell, and the inner layer is softer with intricate collagen structures built like rotating stairways. When a piranha's tooth clamps against the outer shell, the stairway structures bend and rotate to absorb the force without breaking. It's like punching a pillow rather than a pane of glass—the pillow bounces back into shape.
巨骨舌鱼是巨型鱼，成年时的体重近130公斤（300英镑）。但是据泰迪·罗斯福观察，水虎鱼群不会被体型吓倒，所以巨骨舌鱼为抵挡啮咬而进化出了一副盔甲。它们的鳞有两层——外层坚硬，是石化的外壳；里层柔软，里面的骨胶原结构像旋转楼梯那样错综复杂。当水虎鱼牙齿钳住外面的壳时，楼梯似的结构就会弯曲、旋转，将撞击力吸收而且不会破损。就像一拳打在枕头而非玻璃窗上——枕头弹回了原型。
8.看不见的战争
The most abundant lifeform in the ocean is one you'll never see—a family of bacteria collectively known as SAR11. They live in all the world's oceans from the arctic to the tropics, and they're incredibly efficient at their job—converting dissolved carbon into CO2. The most abundant predator in the ocean also exists at the microscopic level—a closely related group of viruses called pelagiphages. And they're waging holy war on the SAR11 bacteria.
你永远看不到海洋里最丰富的生命形式——一个总称为SAR11的细菌科生物。它们遍布世界各大洋，从北极到回归线；它们的工作效率极高——将溶解的碳转换为二氧化碳。海洋生物面对着各种杀手，其中对手最多的也是用显微镜才看得见的生物——一个与病毒密切相关的群体，叫做“pelagiphages”。它们对SAR11细菌发动了圣战。
What's happening is a fiercely competitive evolutionary arms race. Twenty-three years ago, in 1990, the SAR11 bacteria were observed for the first time, and they weren't given a lot of attention. They don't do much; there just happen to be a lot of them. But earlier this year, a routine test of the water off the coast of Oregon found a mass of dead SAR11 cells. Swimming in the same water were the previously unknown pelagiphage viruses, and the researchers watched as the viruses murdered the remaining bacteria cells in front of their eyes.
这是一场进化上激烈的军备竞赛。23年以前，1990年SAR11细菌被首次发现，备受关注。它们没有什么特别，只是数量庞大。但是今年初，对俄勒冈沿岸水体的一项常规检测发现了大量死亡的SAR11细胞。人们不知道这片水里有这种病毒。研究人员眼睁睁地看着病毒杀死剩余细菌细胞。
But the SAR11 are so adept at sharing genetic information that they've managed to stay one step ahead of the pelagiphages, constantly evolving to fight them off. And the viruses aren't far behind. There's already a completely new subfamily of pelagiphage viruses, evolved to prey on the more evolved SAR11 cultures. It's a microscopic war unfolding right in front of us.
但是SAR11擅长分享遗传信息，它们能比这些病毒快一步，不断以进化挫败对方。而病毒落后并不多。它们已经有了一个完整的新的亚科——这就是为捕杀更高级的SAR11生物所做的进化。这场微生物战争正在我们面前兴起。
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