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  • Some are longer than a blue whale.

  • Others are barely larger than a grain of sand.

  • One species unleashes one of the most deadly venoms on Earth.

  • Another holds a secret that's behind some of the greatest breakthroughs in biology.

  • They've inhabited the ocean for at least half a billion years, and they're still flourishing as the sea changes around them.

  • Jellyfish are soft-bodied sea creatures that aren't really fish.

  • They're part of a diverse team of gelatinous zooplankton, zooplankton being animals that drift in the ocean.

  • There are more than 1,000 species of jellyfish, and many others that are often mistaken for them.

  • A noted feature of jellyfish is a translucent bell made of a soft delicate material called mesoglea.

  • Sandwiched between two layers of skin, the mesoglea is more than 95% water held together by protein fibers.

  • The jellyfish can contract and relax their bells to propel themselves.

  • They don't have a brain or a spinal cord, but a neural net around the bell's inner margin forms a rudimentary nervous system that can sense the ocean's currents and the touch of other animals.

  • Jellyfish don't have typical digestive systems, either.

  • These gelatinous carnivores consume plankton and other small sea creatures through a hole in the underside of their bells.

  • The nutrients are absorbed by an inner layer of cells with waste excreted back through their mouths.

  • But the jellyfish's relatively simple anatomy doesn't prevent it from having some remarkable abilities.

  • One kind of box jellyfish has 24 eyes.

  • Scientists think it can see color and form images within its simple nervous system.

  • Four of its eyes are curved upward on stalks.

  • This allows the jellyfish to peer through the surface of the water, looking for the canopy of the mangrove trees where it feeds.

  • In fact, this may be one of the only creatures with a 360-degree view of its environment.

  • The jellyfish's sting, which helps it capture prey and defend itself, is its most infamous calling card.

  • In the jelly's epidermis, cells called nematocysts lie coiled like poisonous harpoons.

  • When they're triggered by contact, they shoot with an explosive force.

  • It exerts over 550 times the pressure of Mike Tyson's strongest punch to inject venom into the victim.

  • Some jellyfish stings barely tingle, but others cause severe skin damage.

  • The venom of one box jellyfish can kill a human in under five minutes, making it one of the most potent poisons of any animal in the world.

  • Other jellyfish superpowers are less lethal.

  • One species of jellyfish glows green when it's agitated, mostly thanks to a biofluorescent compound called green fluorescent protein, or GFP.

  • Scientists isolated the gene for GFP and figured out how to insert it into the DNA of other cells.

  • There, it acts like a biochemical beacon, marking genetic modifications, or revealing the path of critical molecules.

  • Scientists have used the glow of GFP to watch cancer cells proliferate, track the development of Alzheimer's, and illuminate countless other biological processes.

  • Developing the tools and techniques from GFP has netted three scientists a Nobel Prize in 2008, and another three in 2014.

  • But it's jellyfish who may be the most successful organisms on Earth.

  • Ancient fossils prove that jellyfish have inhabited the seas for at least 500 million years, and maybe go back over 700 million.

  • That's longer than any other multiorgan animal.

  • And as other marine animals are struggling to survive in warmer and more acidic oceans, the jellyfish are thriving, and perhaps getting even more numerous.

  • It doesn't hurt that some can lay as many as 45,000 eggs in a single night.

  • And there's some jellyfish whose survival strategy almost sounds like science fiction.

  • When the immortal jellyfish is sick, aging, or under stress, its struggling cells can change their identity.

  • The tiny bell and tentacles deteriorate and turn into an immature polyp that spawns brand new clones of the parent.

  • As far as we know, these are the only animals who found a loophole when facing mortality.

  • That's pretty sophisticated for species that are 95% water and predate the dinosaurs.

Some are longer than a blue whale.

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B2 US TED-Ed jellyfish gfp venom ocean bell

Jellyfish predate dinosaurs. How have they survived so long? - David Gruber

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    Evangeline posted on 2021/05/26
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