The animal that can never die
There's an animal on Earth that can literally never die of old age.
Which one is REALLY true about the Immortal Jellyfish?
The short version
The immortal jellyfish (Turritopsis dohrnii) is barely bigger than a fingernail. When it gets old, sick, or injured it folds its whole body back into a baby polyp and grows up again — repeating the cycle with no known limit. Scientists have watched a single one reverse its age over and over.
Why it's so weird
- ✓The Immortal Jellyfish can avoid dying of old age by folding back into a baby and growing up again.
- ✓The Immortal Jellyfish can repeat its age-reversal cycle over and over with no known limit.
- ✓The Immortal Jellyfish is barely bigger than a fingernail.
- ✓The Immortal Jellyfish rewinds its own cells in a process called transdifferentiation.
You could line up about 271 of them along a 7-year-old!
The full story
This might be the strangest animal that has ever existed. There is a jellyfish on Earth that can literally never die of old age. It's called the immortal jellyfish, and it's barely bigger than your fingernail. Here's the insane part. When a normal animal gets old, sick, or injured, it dies. But this jellyfish doesn't. Instead, its whole body folds back in on itself and transforms all the way back into a baby. The adult literally becomes a child again. And then it grows up, again. And it can repeat that cycle over, and over, and over, with no known limit. Scientists have actually watched a single jellyfish reverse its age again and again in the lab. This trick even has a name. They call it transdifferentiation, where its cells rewind into a younger type. And it works so well that this tiny jellyfish has quietly spread into oceans all over the world. The only way it really dies is if something eats it first. So while everything else on Earth grows old, this little blob just hits the reset button. Forever. Follow for more weird animals.
When this jellyfish is hurt, starving, or just getting old, its grown-up body cells don't keep dying. Instead they actually change into different kinds of cells, a switch scientists call transdifferentiation. Using that trick, the whole jellyfish collapses into a little blob and rebuilds itself as a polyp, the baby stage stuck to the seafloor, which then grows brand-new jellyfish. Because its cells can keep re-switching, there's no known limit to how many times it can restart, though it can still be eaten or get sick and die.
📚 Source: The "Immortal" Jellyfish That Resets When Damaged | American Museum of Natural History ↗In the 1990s a marine biology student kept these jellyfish in lab dishes and, instead of dying, watched the adults turn back into polyps, and researchers later confirmed the same age-reversal again and again under the microscope.
📚 Source: The "Immortal" Jellyfish That Resets When Damaged | American Museum of Natural History ↗Watch the 45-second version
Immortal Jellyfish gallery
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“The Immortal Jellyfish can avoid dying of old age by folding back into a baby and growing up again.”
“The Immortal Jellyfish is the largest arthropod on the planet.”
“The Immortal Jellyfish can repeat its age-reversal cycle over and over with no known limit.”