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  • AHHHH haha just kidding

  • Hey everyone, Julia here for DNews

  • Losing a limb is never something to laugh at. While humans can build awesome robotic

  • arms, other animals have their handy own way of dealing with the problem.

  • Like the moon jellyfish. If this ocean invertebrate loses a limb it simply moves around the other

  • remaining limbs. In a recent study published in the Proceedings of the National Academy

  • of Sciences found that the jellyfish restore functionality in a process the researchers

  • call symmetrization.

  • The jellyfish have to be perfectly symmetrical in order to swim properly. If they can’t

  • swim to find food or swim away from a predator, well theyll be swimming with the fishes.

  • Ortheyll you know get eaten or something. The researchers found that the jellyfish pull

  • off this game of musical arms by using their muscles to push apart the arms as widely as

  • possible. And the whole process is fast, like anywhere from 12 hours to 4 days.

  • While the moon jellyfish use symmetrization to compensate for losing a limb or two, other

  • animals simply regrow their missing body parts.

  • Most of us know that the starfish, excuse me sea stars, can regrow their arms and in

  • some species, they can regrow entire bodies out of limbs. But there’s tons of other

  • animals out there who can regrow limbs too. Like Salamanders, Zebrafish and even some

  • insects like cockroaches. But sometimes limbs aren’t always perfect copies of the original.

  • Like regrown tadpole tails are missing a few nerves.

  • But some animals go one step further, some animals can perfectly regrow their heads.

  • One small animal, Hydractinia, is a head above the rest. Commonly calledsnail fur

  • because it grows on the shells of snails and crabs, this tiny animal can regrow its entire

  • head if it gets bitten off by a hungry predator. But they aren’t alone in this remarkable

  • ability.

  • Planaria also have amazing abilities to regrow themselves. Literally, they can reproduce

  • asexually and just make more copies of themselves. And these guys can also regrow their heads.

  • But what’s weird is, in one study published in the Journal of Experimental Biology, researchers

  • found that worms with regrown heads had the same memories as before. How? Well the researchers

  • aren’t so sure, but think that maybe their memories get stored in other cells in the

  • body and then get imprinted into the new brain when it grows.

  • But what makes these animal’s powers of regeneration so good? In short, stem cells.

  • Stem cells are undifferentiated cells which have the ability to grow into any type of

  • cell or tissue. All animals have these, I mean we grow body parts from scratch as an

  • embryo. But most mammals lose their pluripotent stem cells, or stem cells that are general

  • but can grow into more specific cells later.

  • Some animals like Hydractinia and Planaria use pluripotent stem cells to regenerate themselves.

  • Hydractinia keep their embryonic stem cells for their whole lives. Whenever their heads

  • get eaten up, stem cells flood the neck area and start to build a new head.

  • But other animals have different cellular mechanisms. In salamanders, their limbs regenerate

  • from adult tissue cells. Basically the cells dedifferentiate and form a mass called a blastema.

  • And from this structure, the cells differentiate again and can regrow an arm or a leg. This

  • whole process can take anywhere from a month to three months depending on how old the animal

  • is.

  • But what’s interesting is that some researchers like David M. Gardiner, a professor of developmental

  • and cell biology at the University of California-Irvine, think that all animals might have the ability

  • to grow body parts of pluripotent cells. That some common ancestor that even we share with

  • something like the snail fur was able to keep its stem cells well into adulthood. For some

  • reason ours is just turned off, but he thinks one day well find the on switch.

  • Speaking of animals remarkable ability to regenerate, there might an animal that can

  • live forever!! Check out this short and sweet video from our new show TestTube 101!

AHHHH haha just kidding


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B1 中級

体のパーツを再生することができる8つの動物 (8 Animals That Can Regrow Their Body Parts)

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    羅紹桀 に公開 2021 年 01 月 14 日