Is it really true that some animals live forever?

Immortal jellyfish, and a few similar species, are said to be immortal. But how true is this claim? Dr Helen Scales explains.

Turritopsis dohrnii. © Yiming Chen/Getty

James Bond may have no time to die, but does the same go for the so-called immortal jellyfish? If anything, these tiny jellies, otherwise known as Turritopsis dohrnii, have more in common with Dr Who: they die, then regenerate.

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Most jellyfish exist in alternating states. There are the familiar swimming umbrellas with tentacles – the medusas – which release eggs and sperm that fuse into larvae. These then transform into bottom-dwelling, flower-like polyps, which in turn bud off more medusas.

Immortal jellyfish, along with at least five other jellyfish species, dodge death by hitting rewind. Even after a dead medusa has collapsed into a pile of mush, its cells can grow into polyps.

It’s like a fragment of butterfly wing turning into a caterpillar.

Immortal jellyfish can still die, from predation and disease, but their regenerating abilities make them tough and successful. They’ve hitchhiked in ballast water of ships and now live in seas around the world.


Do you have a wildlife question you’d like answered? Email your question to wildquestions@immediate.co.uk or post it to Q&A, BBC Wildlife Magazine, Immediate Media Company, Eagle House, Bristol, BS1 4ST.

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Main image: Turritopsis dohrnii. © Yiming Chen/Getty