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Some are longer than a blue whale. Others are barely larger than a grain of sand.
有的比蓝鲸还长。有的仅略大于沙粒。
One species unleashes one of the most deadly venoms on Earth.
有的能释放出世界上几乎最毒的毒液。
Another holds a secret that's behind some of the greatest breakthroughs in biology.
有的则隐藏着重大生物学突破的秘密。
They've inhabited the ocean for at least half a billion years,
它们栖息在海洋中长达5亿年，
and they're still flourishing as the sea changes around them.
尽管周围海洋环境不断变化，却依旧蓬勃繁衍。
Jellyfish are soft-bodied sea creatures that aren't really fish.
水母，是软体海洋生物，而非真正意义上的鱼类。
They're part of a diverse team of gelatinous zooplankton, zooplankton being animals that drift in the ocean.
它们是“凝胶状浮游生物”这个大家族的一份子，浮游生物指的是海洋中漂浮的动物。
There are more than 1,000 species of jellyfish, and many others that are often mistaken for them.
总共有1000多种水母，还有很多被误认为水母的生物。
A noted feature of jellyfish is a translucent bell made of a soft delicate material called mesoglea.
水母的显著特征之一是半透明的钟状身体，由叫“中胶层”的柔软细腻的物质构成。
Sandwiched between two layers of skin, the mesoglea is more than 95% water held together by protein fibers.
夹在两层表皮中间的“中胶层”由95%的水分通过蛋白质纤维凝结组成。
The jellyfish can contract and relax their bells to propel themselves.
水母通过收缩和放松钟状躯体向前推进。
They don't have a brain or a spinal cord,
它们没有大脑或脊椎，
but a neural net around the bell's inner margin forms a rudimentary nervous system
但体内边缘分布着的神经网组成了最基本的神经系统，
that can sense the ocean's currents and the touch of other animals.
能够感知洋流和其他生物的接触。
Jellyfish don't have typical digestive systems, either.
水母也不具备典型的消化系统。
These gelatinous carnivores consume plankton and other small sea creatures through a hole in the underside of their bells.
这些胶状肉食动物捕食浮游生物及其他海洋微生物，通过其钟状躯体下方的嘴进食。
The nutrients are absorbed by an inner layer of cells with waste excreted back through their mouths.
营养物质被内层细胞吸收，废物则用嘴吐回去。
But the jellyfish's relatively simple anatomy doesn't prevent it from having some remarkable abilities.
但水母相对简单的解剖结构并不妨碍其具有某些神奇的能力。
One kind of box jellyfish has 24 eyes.
一种盒水母拥有24只眼睛。
Scientists think it can see color and form images within its simple nervous system.
科学家认为它能辨别颜色，并在其简单的神经系统中生成图像。
Four of its eyes are curved upward on stalks.
其中四只眼睛盘旋着分布在视触上。
This allows the jellyfish to peer through the surface of the water,
这使得水母能看见水面上的物体，
looking for the canopy of the mangrove trees where it feeds.
找寻其赖以为生的红树林的树冠。
In fact, this may be one of the only creatures with a 360-degree view of its environment.
事实上，这可能是仅有的拥有360度视角的生物之一。
The jellyfish's sting, which helps it capture prey and defend itself, is its most infamous calling card.
水母用来捕捉猎物和自我防御的触须，是它们最臭名昭著的标志。
In the jelly's epidermis, cells called nematocysts lie coiled like poisonous harpoons.
水母的表皮中含有被称为“刺细胞”的细胞，像涂毒的渔叉成环状分布着。
When they're triggered by contact, they shoot with an explosive force.
受外力刺激时，它们爆发性地射击。
It exerts over 550 times the pressure of Mike Tyson's strongest punch to inject venom into the victim.
以比泰森的致命一击还重550倍的冲击力将毒液注入猎物体内。
Some jellyfish stings barely tingle, but others cause severe skin damage.
有的水母蜇伤只让人发麻，但有的则会造成严重皮肤损伤。
The venom of one box jellyfish can kill a human in under five minutes,
一只盒水母的毒液能在5分钟内致人死地，
making it one of the most potent poisons of any animal in the world.
使其名列世界上最毒的动物毒素之一。
Other jellyfish superpowers are less lethal.
其他常见的水母就没那么致命了。
One species of jellyfish glows green when it's agitated,
有种水母受刺激时发出绿光，
mostly thanks to a biofluorescent compound called green fluorescent protein, or GFP.
主要归功于一种称为“绿色荧光蛋白”的生物荧光化合物，即GFP。
Scientists isolated the gene for GFP and figured out how to insert it into the DNA of other cells.
科学家分离出了GFP的基因，找出了将其植入其他细胞DNA的方法。
There, it acts like a biochemical beacon, marking genetic modifications, or revealing the path of critical molecules.
在细胞内作为生化标记使用，标记出细胞的基因构造，或显示出关键分子的移动路径。
Scientists have used the glow of GFP to watch cancer cells proliferate,
科学家利用GFP发出的光观察癌症细胞的增生，
track the development of Alzheimer's, and illuminate countless other biological processes.
追踪阿兹海默症的发展，并揭示无数其他的生物过程。
Developing the tools and techniques from GFP has netted three scientists a Nobel Prize in 2008, and another three in 2014.
利用GFP研发出的工具和技术，使3位科学家共同收获了2008年的诺贝尔奖，另外3位于2014年获奖。
But it's jellyfish who may be the most successful organisms on Earth.
但水母可能才是地球上最成功的生物。
Ancient fossils prove that jellyfish have inhabited the seas for at least 500 million years, and maybe go back over 700 million.
古化石证明水母在海洋中栖息了至少5亿年，甚至7亿年。
That's longer than any other multiorgan animal.
这比任何多器官生物都要长。
And as other marine animals are struggling to survive in warmer and more acidic oceans,
而且在其他海洋生物互相竞争以生存在更温暖酸度更高的海洋里时，
the jellyfish are thriving, and perhaps getting even more numerous.
水母一族正蓬勃繁衍，数目可能变得更加不可估量。
It doesn't hurt that some can lay as many as 45,000 eggs in a single night.
有的一晚可以轻松产下45000个卵。
And there's some jellyfish whose survival strategy almost sounds like science fiction.
还有些水母的求生策略听起来简直像科幻小说。
When the immortal jellyfish is sick, aging, or under stress, its struggling cells can change their identity.
当神奇的水母生病、衰老或者受到压力时，体内挣扎的细胞可以改变其特性。
The tiny bell and tentacles deteriorate and turn into an immature polyp that spawns brand new clones of the parent.
微小的钟状身体和触须开始恶化，变成不成熟的息肉，并生成全新的母体的克隆体。
As far as we know, these are the only animals who found a loophole when facing mortality.
据我们所知，这些是仅有的能在面临死境时找到一线生机的动物。
That's pretty sophisticated for species that are 95% water and predate the dinosaurs.
这对于这样一个身体由95%水分组成且早于恐龙诞生的生物来说是相当高级的。
