Can a Jellyfish Unlock the Secret of Immortality?

Sommer was conducting research on hydrozoans, small invertebrates that, depending on their stage in the life cycle, resemble either a jellyfish or a soft coral. Every morning, Sommer went snorkeling in the turquoise water off the cliffs of Portofino. He scanned the ocean floor for hydrozoans, gathering them with plankton nets. Among the hundreds of organisms he collected was a tiny, relatively obscure species known to biologists as Turritopsis dohrnii. Today it is more commonly known as the immortal jellyfish.

Sommer kept his hydrozoans in petri dishes and observed their reproduction habits. After several days he noticed that his Turritopsis dohrnii was behaving in a very peculiar manner, for which he could hypothesize no earthly explanation. Plainly speaking, it refused to die. It appeared to age in reverse, growing younger and younger until it reached its earliest stage of development, at which point it began its life cycle anew.

Sommer was baffled by this development but didn’t immediately grasp its significance. (It was nearly a decade before the word “immortal” was first used to describe the species.) But several biologists in Genoa, fascinated by Sommer’s finding, continued to study the species, and in 1996 they published a paper called “Reversing the Life Cycle.” The scientists described how the species — at any stage of its development — could transform itself back to a polyp, the organism’s earliest stage of life, “thus escaping death and achieving potential immortality.” This finding appeared to debunk the most fundamental law of the natural world — you are born, and then you die.

One of the paper’s authors, Ferdinando Boero, likened the Turritopsis to a butterfly that, instead of dying, turns back into a caterpillar. Another metaphor is a chicken that transforms into an egg, which gives birth to another chicken. The anthropomorphic analogy is that of an old man who grows younger and younger until he is again a fetus. For this reason Turritopsis dohrnii is often referred to as the Benjamin Button jellyfish.

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Solving the mystery of ageing

Why do we get older? When do we die and why? Is there a life without ageing? For centuries, science has been fascinated by these questions. Now researchers from Kiel (Germany) have examined why the polyp Hydra is immortal – and unexpectedly discovered a link to ageing in humans. The study carried out by Kiel University together with the University Medical Center Schleswig-Holstein (UKSH) will be published this week in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). It was funded by the German Research Foundation DFG.