The immortal jellyfish

Discover how these jellies reverse their maturity in a continuous cycle

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Do you ever wish you could jump back in time to when you were younger and start life again? As life passes us by, our bodies are designed to grow, age and eventually die. However, not all species follow this cycle. Meet the immortal jellyfish, Turritopsis dohrnii. Achieving what is merely a superhero fantasy for many of us, age doesn’t kill these tiny, bell-shaped marvels. Instead of following just one life cycle, the jellyfish can ride the cycle continuously, or until they find themselves in the jaws of their fi sh predators. Reverting their bodies back to their younger state, they have multiple chances at life.

Super-powered doesn’t necessarily mean super-sized. At their largest they are still less than five millimetres both in height and width. These jellyfish were first discovered in 1883 in the Mediterranean Sea, but only gained their new moniker of the immortal jellyfish in the mid-1990s. While being studied in a lab, the jellyfish skipped the fertilisation stage and regressed in maturity. It is thought that the immortal jellyfish might use this skill in cases of emergency, such as in the stressful situation of being contained in a small space.

A constant cycle

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1. Egg
The jellyfish’s life begins when the female’s egg is fertilised by a male.

2. Planula larva
When the eggs have developed into planula larvae, they are released into the ocean, beginning a brief free-swimming stage before settling on the sea floor.

3. Fixed planula
Attached to the floor via one end, the planula stops to develop some more jellyfish-like features. It starts to grow tentacles and a mouth.

4. Polyp
When attached to the hard surface, it begins to transform into a polyp. Sometimes remaining in this stage for several years, it is this cylindrical, pre-jellyfish stalk that adults can later revert back to.

5. Grown polyp
The polyp continuously splits its cells to produce numerous clones of itself. When doing this its height grows.

6. Baby jellyfish
Layers of the polyp split from the top of the cylinder, becoming mobile creatures that can travel the sea. These are baby jellyfish called ephyrae.

7. Juvenile
The young jellyfish gradually grows and matures. It begins to adopt the larger, smooth bell of the adult jellyfish.

8. Fully grown adult
With its complete umbrella-shaped bell and developed tentacles, the jellyfish has reached full maturity. At this point it has the option to relive most of the cycle by modifying its cells.


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