The Key to Immortality: Jellyfish

Is this miracle even in the picture?

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Deep in the vast abyss of the ocean, roams a creature that might hold the elixir to immortality. When this creature of wonder dies, it rises again from its own remains…

Humans, throughout history, have embroiled themselves in the quest for immortality. Beginning from early pursuits into alchemy to modern-day anti-aging means, the eagerness to live eternally goes as far back as the human awareness of mortality. Would Nicholas Flammel, the father of alchemy, ever have guessed that one of the earthly holders of immortality could be a floating wad of goo? Yes, you heard that right!  A species of jellyfish, the ‘Turritopsis dohrnii’, is known to be ‘biologically immortal’.

The ‘Turritopsis dohrnii’

Turritopsis dohrnii is a species of jellyfish that inhabits the Mediterranean Sea and the waters of Japan.  Transparent and tiny, this jellyfish can grow to be only the size of a fingernail at most. The biological structure of this species of jellyfish is simple: mats of nerves instead of a brain, a single opening that allows food to enter and waste to exit, and no heart. This species does not even have fully-developed eyes, and simply have light-sensitive spots that barely manage to differentiate between light and dark.  In some sense, they are just floating wads of goo.

https://thebiologist.rsb.org.uk/images/biologist/Features/Jellyfish-web.png

The Life and Times of the Jellyfish

Turritopsis dohrnii is one of the very few recorded cases of biologically immortal animals. These jellyfish start off their life as larvae called ‘planula’. These ‘planula’ swim about in the ocean for a while and eventually settle down to the sea-floor. Here, they attach themselves to the sea-bed and develop into a colony of ‘polyps’. The ‘polyps’ develop into a tree-like structure, and grown jellyfish — known as ‘medusae’ — then detach from the ends of the branches. At this stage, these jellyfish are free to swim about, and eventually become sexually mature.

Immortal jellyfish life cycle

The Secret of ‘Immortality’

By this point, you’re probably thinking how a creature so absurdly simple in structure and function can accomplish such a feat. Yet it is precisely this simplicity which grants it its coveted ‘immortality’.

When we say that the T. dohrnii jellyfish doesn’t ‘die’, we don’t mean that in the traditional sense; it does not reach a certain age and stay there. Rather, we mean that it can ‘cheat’ death by converting itself back to an adolescent form. This shields the jellyfish from many life-threatening conditions, such as unexpected environmental changes, physical assault, and starvation. It does this through a process known as ‘trans-differentiation’.

Trans-differentiation is the process by which one cell type is converted to another.  Think of it like this: a caterpillar metamorphosizes into a cocoon, which then develops into a butterfly. When the butterfly is about to die, it sheds off all its essential structures and becomes a caterpillar again. This cycle repeats indefinitely. Similarly, when a T. dohrnii jellyfish is exposed to a stressful situation, it will attempt to cheat death by getting a ‘second chance’. It will transform its existing cells into younger versions, becoming sperm cells or even egg cells. It will shrink in size and withdraw its tentacles, sinking to the ocean floor. It will then revert back to the ‘polyp’ stage, which is the first stage of the jellyfish’s life. This results in a ‘polyp’ colony again, spawning hundreds of jellyfish which are identical to the original adult. In theory, this process can extend infinitely, rendering the T. dohrnii as a ‘biologically immortal’ organism.

The Bad News

So does this mean that if we somehow managed to transfer the DNA of the immortal jellyfish into a human cell, we would be able to attain immortality? Well, it’s not that simple.

Jellyfish are simpler organisms compared to humans. They do not have complex structures such as brains or hearts, nor do they have a developed consciousness (as far as we know). On the other hand, the human body is crazily complex and grows in one direction only, unless you’re Benjamin Button. ‘De-maturing’ biological structures such as muscles and bones is possible, but reversing the development of the brain is difficult, mainly because of its extreme complexity. Moreover, if one were to convert the brain back to an adolescent stage, they would be undoing a great deal of psychological development. In theory, they would be wiping out not only mental growth but also memories. This idea is simpler for jellyfish because they don’t really possess the kind of brain development which humans have. Thus, for humans, this poses a great difficulty.

What most people mean by ‘immortality’ would be to reach a certain age and to stay there for the entirety of their lives. Destroying most of your body systems to become crude, the cellular mesh isn’t exactly ideal.

… And the Good News

Despite all, the Turritopsis dohrnii is still of biological and pharmaceutical interest. The process of trans-differentiation could help replace damaged and diseased cells, facilitating stem-cell research. It could also help in curing neurodegenerative disorders such as Alzheimer’s and Parkinson’s, by replenishing damaged nerve cells in the brain. A group of researchers from the Gladstone Institute of Cardiovascular Disease at the University of California was successful in using trans-differentiation for converting architectural cells in the heart to behave like cardiac muscle cells.

For the time being, immortality still appears to be a distant idea for human civilization. Yet taking cues from the wonderment that is T. dohrnii can help us make big developments in the field of biological science.

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