The Jellyfish That Rewinds Time
It sounds like a sci-fi plot, but it’s real: a tiny jellyfish that can actually reverse its life cycle instead of dying
Image source: Natural History Museum
Meet Turritopsis dohrnii, better known as the “immortal jellyfish.” Smaller than a fingernail, this translucent hydrozoan has a trick no other animal seems to match. When stressed or injured, it doesn’t just give up—it transforms back into an earlier life stage, becoming a polyp again. From there, it grows into a medusa all over, essentially resetting the clock.
Scientists call the process transdifferentiation, where the jellyfish’s specialized cells reprogram themselves into different kinds of cells. Imagine a butterfly turning back into a caterpillar—then growing into a butterfly once more. In theory, this loop can go on forever.
Of course, “immortal” doesn’t mean untouchable. Predators, disease, or environmental stress can still end their lives. But in perfect conditions, they may never die of old age—earning their place as one of nature’s strangest marvels.
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