🎬 Jellyfish (水母)
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Jellyfish can be found all over the world from deep oceans to shallow coastal areas.世界各地从深海到浅海沿岸水域都能找到水母的踪迹。
They've been around for hundreds of millions of years.它们已经在地球上生存繁衍了数亿年之久。
Boneless, brainless, and bloodless, jellyfish are some of the most diverse and fascinating creatures in the sea.没有骨骼、大脑和血液，水母是海洋中最奇妙多样的生物之一。
Jellyfish aren't actually fish, with thousands of different species.水母实际上并不是鱼类，且包含数千个不同物种。
In two different biological phyla, jellyfish is more of a broad term than anything else.分属两个不同生物门类，“水母”更多是一个宽泛的统称。
Unlike fish, which have backbones, jellyfish are invertebrates.与拥有脊椎的鱼类截然不同，水母属于无脊椎动物。
Jellyfish got their common name from the jelly-like material they're made out of, called mesoglia.水母的通用名称源于构成其身体的果冻状物质，称为中胶层。
In recent years, scientists have started using the umbrella term sea jellies to clear up the confusion.近年来，科学家们开始使用更准确的统称“海蜇/水母类”(sea jellies)来消除混淆。
There is an immortal jellyfish.自然界中存在一种真正“永生不死”的水母。
Jellyfish can reproduce sexually by releasing sperm and eggs into the water, and reproduce asexually by splitting into two or cloning.水母既可以通过向水中释放精卵进行有性繁殖，也可以通过分裂或克隆进行无性繁殖。
But at least one jellyfish can actually reverse the aging process.但至少有一种水母甚至能够真正逆转自身的衰老过程。
The turetopsis dorniii has earned the nickname the immortal jellyfish for being able to undergo a process called transdifferentiation.灯塔水母因能够经历被称为“转分化”的过程而赢得了“永生水母”的称号。
An adult or juvenile under stress, instead of dying, can revert back to a pollen and begin the life cycle all over again.处于环境压力下的成体或幼体水母不会死亡，而是能够退回水螅体阶段重新开始生命周期。
It is the only animal in the world that is known to be able to reverse its life cycle.它是世界上已知唯一能够完全逆转生命周期的奇特动物。
Box jellyfish are the most venomous marine animals in the world.箱形水母是世界上毒性最强的海洋生物。
Jellyfish stings are a common fear of beachgoers worldwide, and with good reason.被水母蛰伤是全球海滩游客共同的恐惧，而且这种恐惧完全有据可依。
There are an estimated 150 million jellyfish stings reported annually.据估计，每年全球报告的水母蛰伤事件高达1.5亿起。
And while not all jellyfish have stingers, the Australian box jellyfish, or Kyronex fleckery, is considered the most venomous marine animal in the world.虽然并非所有水母都有毒刺，但澳大利亚箱形水母被公认为是世界上毒性最烈的海洋生物。
Its deadly tentacles can grow up to ten feet long.其致命的触手最长可长达10英尺（约3米）。
Humans and other animals that are unlucky enough to get stung may experience paralysis, cardiac arrest,不幸被蛰到的人类和其他动物可能会出现瘫痪、心脏骤停，
and even death within just a few minutes.甚至在短短几分钟内就会丧命。
Jellyfish are 95% water.水母身体的95%都是水。
To put this in perspective, the average adult human male is about 60% water.作为对比，成年人类男性的身体含水量约为60%。
But jellyfish are much simpler than humans.但水母比人类的构造要简单得多。
They don't have hearts, blood, brains, or bones.它们没有心脏、血液、大脑或骨骼。
Jellyfish do have very basic sensory organs in their bells and tentacles,水母在伞盖和触手表面确实拥有极其基础的感觉器官，
and a simple digestive cavity which serves as a stomach, intestine, and isophagus.以及一个兼作胃、肠和食道的简单消化循环腔。
If a jellyfish washes up on the beach, it will mostly evaporate due to the high water content.如果水母被冲上沙滩，由于含水量极高，绝大部分身体很快就会直接蒸发殆尽。
Groups of jellyfish are called blooms, swarms, or smacks.成群聚集在一起的水母被称为水母潮(blooms)、水母群(swarms)或水母团(smacks)。
Jellyfish blooms can form quickly, and scientists think that the jellies get together for mating purposes.水母潮能够迅速聚集形成，科学家认为它们聚集主要是为了交配繁衍。
In extreme cases, the bloom can be so dense, there are more jellyfish than water in a given area.在极端情况下，水母聚集的密度甚至会超过水体体积。
They can be as small as a cubic meter, or cover hundreds of square miles.它们的规模小则仅一立方米，大则可覆盖数百平方英里的海域。
While these blooms are natural, they've caused problems all over the world.虽然这些水母群聚是自然现象，但它们也曾给全球各地带来严重问题：
Such as clogging fishing equipment in Mexico, destroying Chinese ships,例如堵塞墨西哥的捕鱼设施、倾覆破坏船只，
and closing beaches in Australia and Europe.以及导致澳大利亚和欧洲的海滩被迫关闭。
There is still so much to learn about these floating mysterious creatures.关于这些漂浮的神秘海洋生物，我们仍有无尽的未知亟待探索。
Scientists believe that there may be as many as 300,000 species of jellyfish that we haven't yet discovered.科学家推测，海洋深处可能有多达30万种水母至今尚未被人类发现。
Before You Watch · p.41
While You Watch · p.42
Critical Thinking · Speculating
Some jellyfish species are bioluminescent. How might this ability be useful to them in open ocean waters? (e.g. startling predators, illuminating prey, or confusing attackers)
Vocabulary Review · p.42
Reading A · Living Light
Reading B · Feathers of Love
🏆 Reading Explorer 4 · Unit 2 大满贯荣誉证书
2A Living Light、2B Feathers of Love 与 Jellyfish (水母) 视频拓展