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  • As you may have noticed,

  • I tend to be a pretty easy going guy.

  • But like most people,

  • I occasionally get somewhat irritable,

  • and that usually happens when one of two things happen:

  • Either I'm hungry, or I'm really stressed out.

  • Note that you do not want to be around me when I'm both hungry and really stressed out.

  • There are a number of ways that I can deal with these situations:

  • I eat, I exercise. Sometimes I just scream.

  • One thing I cannot do, though,

  • it would be really nice,

  • would be to revert back to a simpler time,

  • back to when I was eight-year-old Hank.

  • But there is an organism, in this great wide world of ours,

  • that can do that very thing.

  • [intro music]

  • This, my friends, is Turritopsis Dohrnii.

  • Otherwise known as Turritopsis Nutricula.

  • Other, otherwise known as The IMMORTAL JELLYFISH.

  • You heard me correctly; this little guy is the only animal that we know of

  • that is capable of reverting back to a younger version of itself.

  • And it does this, you've probably guessed,

  • when it's facing starvation or other stresses in its environment.

  • The question, though, is how does this happen,

  • and how can I get me some of it?

  • Okay, so because I know you are super curious, here is the typical life cycle of a jellyfish.

  • We've got the fertilized egg, which becomes a larva,

  • which sinks to the bottom of the ocean,

  • attaches itself to something and becomes a polyp,

  • which over time transforms itself into a free-swimming bell-shaped Medusa,

  • AKA a jellyfish, with 80 to 90 tentacles. Simple, right?

  • Since our friend, The Turritopsis, is a kind of Plankton...

  • Plankton is, by the way, a word for anything that doesn't really move itself around in the ocean;

  • it just gets moved around by the ocean:

  • Drifting organisms.

  • And Turritopsis is a source of nutrition,

  • so it often gets eaten by other organisms

  • or, you know, killed off by disease,

  • so it's technically not immortal if it gets eaten.

  • But the amazing stuff happens when this dime sized jellyfish

  • somehow avoids getting eaten but then can't find enough food or is injured or

  • is otherwise stressed by the environment this is the point that the jellyfish

  • goes all benjamin button on is throwing its life cycle into reverse the bell and

  • all those tentacles deteriorate and it eventually becomes assist this cyst has

  • the ability to reactivate genetic instructions from earlier in its life

  • cycle and actually starts creating new polyp cells and from there the life

  • cycle process begins again as the polyp through the beauty of asexual

  • reproduction releases many identical copies of itself scientists have said

  • that in theory this process could repeat indefinitely making the jellyfish

  • technically immortal it may seem like science fiction like there could be only

  • one jellyfish

  • what's actually happening here as the jellyfish transformed cells into a

  • younger state is called transdifferentiation this is one mature

  • cells that have already been assigned to function like lung cells or skin cells

  • become different kinds of cells in the case of this jellyfish that might mean

  • converting a muscle cell into a nerve cell or even a sperm and egg cell among

  • animals transdifferentiation is not

  • unique to these jellyfish for example if you take the lens out of the eye of a

  • chicken

  • the iris cells will actually develop into Lens cells unlike the jellyfish

  • though the chicken cannot revert its entire body back into an egg

  • though yeah that would be pretty awesome. the story of the turritopsis is important to

  • scientists because we're constantly looking for ways to regenerate new

  • tissue

  • usually that process involves stem cells or unassigned cells that haven't been

  • given genetic instructions to become a nerve cell or a bone cell or a liver cell

  • turns differentiation doesn't require that the problem is we have no idea what

  • signals are being sent to these cells to to change their type we just don't

  • understand how it works and it's not entirely clear that even possible

  • in mammals like us of course that doesn't mean that studying this

  • jellyfish isn't going to be tremendously useful for us if this thing has cells

  • that can switch themselves on and off when they're in peril prove very useful

  • for cancer research

  • imagine if we could isolate a cancer cell and just turn on their young and

  • healthy cell instructions again for now the turritopsis remains the only animal

  • that we know of that can regenerate its entire body which might go a little ways

  • to explain why the population of this jellyfish is exploding worldwide of course it is

  • it's practically immortal always so much good information here youtube.com slash

  • scishow you can go and subscribe right now if you haven't and you will get this

  • good stuff in your subscription box constantly if you have questions or

  • suggestions for us you can hook up with us on facebook or on twitter and always

  • of course in the YouTube comments below

  • goodbye!

  • [Outro Music]

As you may have noticed,

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永遠に生きるには?クラゲになる (How to Live Forever? Be a Jellyfish)

  • 101 5
    robert に公開 2021 年 01 月 14 日
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