Immortal Jellyfish

In the first chapter, we were talking about the abilities of the Phoenix. One of them was regeneration. Nevertheless, Phoenix is just a mythological creature. The question is: Does exist any immortal animal? The answer is YES. In this chapter, we will be talking about Turritopsis dohrnii - the backward-aging jellyfish.

Firstly, we should look close up at this jellyfish. Fully grown, Turritopsis dohrnii is only about 4.5 mm across, smaller than a pinky nail. It has a bright-red stomach and the edges are lined up to 90 white tentacles. It was first discovered in the 1880s in the Mediterranean sea. The thing that makes this creature so incredible is that it is biologically immortal.

Now, let's look at the typical life cycle of a jellyfish. We´ve got the fertilized egg which becomes a larva, that sinks to the bottom of the ocean, attaches itself to something, and becomes a polyp, which over time transforms itself into an adult bell-shaped jellyfish.
Nevertheless, Turritopsis dohrnii is part of plankton so its end is often in a stomach of a whale of other animals living in the ocean so it´s technically not immortal if it gets eaten but it cannot die from old age. In a situation when Turritopsis suffers from starvation, physical damage, or other crises it transforms all of its existing cells into a younger state, basically reverses its life cycle, becomes a cyst. The cyst can reactivate genetic instructions from earlier in its life cycle and by asexual reproduction creates new polyp cells. From the cells become polyp again and later transform into an adult jellyfish and this process can be repeated over and over.

The transforming of cells into a younger state is called transdifferentiation. It means that one mature cell that has a function of for example a lung cell becomes a different kind of cell, for example, a skin cell. In the case of this jellyfish that might mean converting a muscle cell into a nerve cell or even a sperm and egg cell.

This process has inspired many researchers to find a way of using stem cells to renew damaged or dead tissue in humans so one day in the future humans may live for hundreds or even thousands of years.

Karolína Walterová