Immortality. A concept that has been desired all throughout life; from Imperial China till now. After all, the concept of living forever seems appealing at first; although nobody on this Earth has ever achieved it.

 

Or have they?

 

The Turritopsis dohrnii, a species of jellyfish, have been closely inspected by scientists and biologists ever since it was found out that they were essentially immortal. Dubbed the “immortal jellyfish,” it was discovered by scientists in 1883, but its ability to rewind the clock was discovered 100 years later in the 1980s. How exactly does this immortality work?

When a medusa, a fully grown jellyfish, of the T. dohrnii species is in danger, for example  being mortally injured or experiencing starvation, it turns into a blob, retracting its tentacles and being unable to move or swim. It then regresses to its previous life stage, a polyp. Polyps are a stage in a jellyfish’s life cycle where it is attached to the ocean floor, serving as a structure that produces a dozen or more jellyfish to swim. The jellyfish then leave the polyp there, akin to a butterfly leaving its cocoon behind, but the polyp can continue to produce more jellyfish unlike a cocoon. This essentially makes the jellyfish immortal, as it is able to continue living and repeat the process infinitely. This process is called transdifferentiation, and can be likened to a flower turning back into a seed right before dying. Transdifferentiation alters the medusa’s cells’ gene pattern, cellular function and morphology to those of its previous life stage, a polyp. The only animal known to perform it is the T. dohrnii, making it extremely rare. They can still be killed, however, being prey to lots of marine life like sea turtles and fish. Their polyps can also be eaten by sea slugs and crustaceans, meaning that their potentially infinite life is not always guaranteed. However, with perfect conditions, T. dohrnii has the ability to live forever.

 

T. dohrnii used to live exclusively in the Mediterranean Sea, but they have now spread to multiple oceans across the globe. Experts attribute their spread to humans, believing that the jellyfish unintentionally hitchhike with cruises and ships, being sucked inside ballast water.  Its immortality allows it to survive conditions that other marine life could not. For instance, a lack of food and starvation would kill most marine animals, but T. dohrnii can simply revert back to a polyp to survive this. They are not noticed often because of their appearance, which explains how they were able to spread across oceans so quickly without anyone realizing. Being translucent and 4.5 mm wide, smaller than the nail on your pinky, it would be near impossible for anyone to notice this impressive critter. 

 

The jellyfish are being studied by scientists frequently, as their transdifferentiation could help find new ways to regenerate lost or damaged tissue. Researchers are investigating ways to induce this amazing process in human cells, with lots of experiments being performed. By analyzing and examining transdifferentiation, taking note of its molecular mechanisms, new approaches can be formulated to repair the human body. The study of T. dohrnii offers exciting and innovative pathways for medicine; the future is now, and we’re living in it!

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Works Cited
Osterloff, Emily. “Immortal Jellyfish: The Secret to Cheating Death.” Natural History Museum, www.nhm.ac.uk/discover/immortal-jellyfish-secret-to-cheating-death.html. Accessed 3 Mar. 2024. 

Piraino, Stefano, et al. “Reversing the Life Cycle: Medusae Transforming into Polyps and Cell Transdifferentiation in Turritopsis Nutricula (Cnidaria, Hydrozoa).” Biological Bulletin, vol. 190, no. 3, 1996, pp. 302–12. JSTOR, https://doi.org/10.2307/1543022. Accessed 5 Mar. 2024.

Boero, Ferdinando. “Everlasting Life: The ‘immortal’ Jellyfish.” RSB, Royal Society of Biology, thebiologist.rsb.org.uk/biologist-features/everlasting-life-the-immortal-jellyfish. Accessed 5 Mar. 2024.