You're swimming in the ocean when something brushes your leg.
当你在海洋中游泳，有东西擦到了你的腿。
When the tingling sets in, you realize you've been stung by a jellyfish.
等你感觉到刺痛时，这才知道你是被水母蛰伤了。
How do these beautiful, gelatinous creatures pack such a painful punch?
这些美丽的、凝胶状的生物是怎样藏有如此重击呢？
Jellyfish are soft because they are 95% water and are mostly made of a translucent gel-like substance called mesoglea.
水母的质感很软，因为它们95%都是水，而且大部分是由一种叫中胶层的半透明凝胶体物质组成的。
With such delicate bodies,
有如此娇嫩柔弱的身体，
they rely on thousands of venom-containing stinging cells called cnidocytes for protection and prey capture.
它们依靠上千个含毒液的刺细胞来保护自己以及捕猎。
Even baby jellyfish, the size of a pencil eraser, have the ability to sting.
甚至连一块铅笔橡皮大小的水母宝宝都可以蜇人。
Larval jellyfish, ephyrae, look like tiny flowers pulsating in the sea.
幼小的水母形似小花朵在大海中跳动着。
As they grow, they become umbrella-shaped with a bell at the top and descending tentacles around the margin.
随着它们一点点成长，它们会呈现出雨伞状，顶部就是伞盖体，周边有向下垂的触角。
The largest species of jellyfish, the lion's mane,
最大的一种水母，狮鬃水母，
has tentacles that can extend more than 100 feet, longer than a blue whale.
它的触角能够长达100英尺，比蓝鲸还要长。
These tentacles contain most of the stinging cells, although some species have them on their bells, too.
大多数刺细胞都在它的触角中，有些品种的水母在它们的伞盖体上也有刺细胞。
Venom is ejected via a nematocyst, a whip-like hollow tubule, which lies coiled under high osmotic pressure.
毒液的注射是通过刺丝囊，一个鞭状的空心小管，它在高渗透压下是盘曲着的。
When mechanical or chemical stimuli activate an external trigger,
当外界机械性或化学性的刺激触发它之后，
the lid of the cell pops open and sea water rushes in.
细胞盖便会打开，海水就会涌进来。
This forces a microscopic barbed harpoon to shoot out, penetrate and inject venom into its victim.
这促使一个微小的鱼叉状刺丝发射了出来，刺破它的目标并注入毒液。
Nematocyst discharge can occur in less than a millionth of a second,
刺丝囊能在一百万分之一秒内发射毒液，
making it one of nature's fastest biomechanical processes.
是自然界中最快的生物力学过程之一。
Nematocysts can continue to fire even after a jellyfish has died,
刺丝囊能够在水母死后持续发射毒液，
so it's important to remove lingering tentacles stuck to the skin.
所以一定要将缠在皮肤上的触角清除。

Rinsing with vinegar will usually render undischarged nematocysts inactive.
用醋冲洗通常会使刺丝囊停止发射毒液。
Seawater can also help remove residual nematocysts.
海水也有助于清洗残留的刺丝囊。
But don't use fresh water because any change in salt balance
但是千万不要用淡水冲洗，因为一旦破坏了水盐平衡，
alters the osmotic pressure outside of the cnidocyte and will trigger the nematocyst to fire.
刺丝囊外的渗透压力就会改变，将会触发刺丝囊继续释放毒液。
That's why urinating on the affected area, a common folk remedy,
这就是为什么用尿液冲洗伤口，一个广为流传的民间偏方，
may do more harm that good, depending on the composition of the urine.
由于其组成成分可能会使伤口更加疼痛。
Most jellyfish stings are a painful nuisance, but some can be deadly.
大多数水母蛰伤都是些痛苦的麻烦事，但是有些蛰伤却是致命的。
An Indo-Pacific box jelly, also called a sea wasp,
印度太平洋箱型水母，俗称海黄蜂，
releases venom which can cause contraction of the heart muscles and rapid death in large doses.
释放的毒液可以导致心肌收缩，大剂量则会导致猝死。
There's an anti-venom, but the venom is fast-acting, so you'd need immediate medical intervention.
虽然有抗毒血清，但是毒液见效很快，所以伤者必须立即就医。
Despite the impressive power in their tentacles, jellies aren't invincible.
尽管它们的触角很强大，水母并不是无敌的。
Their stinging cells are no match for the armor of thick-skin predators, like the leatherback turtle and ocean sunfish.
它们的刺细胞无法对抗一些捕食者坚硬的盔甲，比如棱皮龟和翻车鱼。
These predators both have adaptations that prevents slippery jellyfish from escaping after they are engulfed:
这些捕食者都有对抗水母的武器，防止它们被吞食之后逃脱：
backwards pointing spines in the turtle's mouth and esophagus and recurved teeth behind the sunfish's cheeks.
乌龟口中和食道中向后倾倒的棘刺，还有翻车鱼腮后面弯曲的牙齿。
Even tiny lobster slipper larvae can cling to the bell of a jellyfish and hitch a ride,
连幼小的虾蛄都可以粘在水母的伞盖体上搭顺风车，
snacking on the jelly while they preserve their own energy for growth.
一边吃水母上的胶，一边保留能量生长。
Small agile fish use the jellies as moving reefs for protection, darting between tentacles without ever touching them.
敏捷的小鱼把水母当成移动的珊瑚礁来保护自己，在触角之间穿梭，却丝毫不碰到它们。
Nudibranchs, which are sea slugs covered in protective slime,
裸鳃类物种，一些用粘液保护自己的海蛞蝓，
can actually steal the jelly's defenses by eating the cnidocytes
甚至可以吃掉刺丝囊，夺走水母的防御功能，
and transferring them to specialized sacks for later use, as weapons against their own predators.
把它们转移到专门的囊中以待后用，作为对付它们敌人的武器。
Even humans might benefit from the sting of a jellyfish one day.
连人类在未来也有可能从水母蜇人的能力中获利。
Scientists are working on manipulating cnidocytes to deliver medicine,
科学家们正在实验试图操控刺丝囊来运送药物，
with nematocysts rarely 3% of the size of a typical syringe needle.
因为刺丝囊只有普通注射器针头3%的大小。
So, the next time you're out in the ocean, be careful.
所以，下次你去海边的时候，一定要小心。
But also, take a second to marvel at its wonders.
同时，也不妨感叹一下它的神奇。