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A jellyfish's return to an earlier life stage

The tiny jellyfish Turritopsis dohrnii can sometimes reverse part of its development, returning from a swimming medusa to an earlier polyp stage. That remarkable ability explains its “immortal” nickname, but restarting development is different from being impossible to kill.

3–7 min

Questions you could explore

  • What changes during the reversal, and what makes the resulting animal the same individual?
  • How does reversing a life stage differ from surviving indefinitely in the wild?

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