An immortal – someone who never dies. Have you ever come across any such creature? Of course, the tortoises live for very long but they are still not immortal. Well, today let us look at one such organism on earth. It is called the immortal jellyfish.
Have u seen jellyfishes? – The nice pretty umbrella-like creatures that swim around the sea. A jellyfish species discovered in the Mediterranean Sea in the 1880s, called Turritopsis dohrnii, is the only animal known to possess the ability to reset itself when it is faced with harsh environments.
Image adapted from: Australian Academy of Science https://www.science.org.au/
The egg of this jellyfish becomes a larva called a planula, which swims around freely before settling on the seafloor and then developing into a colony of polyps. Polyps produce free-swimming, genetically identical tiny immature jellyfish-like forms called medusae, which mature into adulthood in a matter of weeks. When fully grown, Turritopsis dohrnii is less than 4.5 mm in diameter, and its transparent bell shows a red stomach with up to 90 white tentacles lining its edges. Although these creatures are tiny, they are extremely resilient. In response to physical damage or starvation, they revert to polyps, which allows them to continue their development. So basically when stressed during the immature medusae stage they transform back into polyps since the conditions are not too good for survival into a mature stage.
Thus it may seem that these born-again colonies can live forever since they will eventually produce medusae that are genetically identical to the injured adults. This phenomenon was first observed in the 1990s, and the species has evolved the name “immortal” to describe its characteristics.
Wonder how this happens? It is believed to be caused by transdifferentiation, a process rare in nature that is particularly relevant to medicine due to its potential applications. Differentiation is when a primitive cell becomes a specialized cell of the living organism. In transdifferentiation, in the immortal jellyfish, the specialized cell does a reverse turn and becomes unspecialized before then differentiating again. Thus a cell that is specialized for a particular tissue can undergo transdifferentiation in order to become another type of cell within the same tissue. Essentially, it is an efficient way to recycle cells and an area of study in stem cell research that could help scientists replace cells that have been damaged by disease.
Image from https://thebiologist.rsb.org.uk/
Due to this resilience of these jellyfishes, they are also aggressive invaders in the marine environment and also travel to faraway places. Armed with such a strategy it comes as no surprise how they manage to survive any adverse conditions.
There may be very soon a time when we would unravel the means by which the jellyfish manages to do so and probably take some tips to prolong the lives of human beings as well. Wanna Live forever??? May be possible very soon…
To read more on this wonderful sea creature:
https://www.science.org.au/curious/earth-environment/animals-can-live-forever
https://thebiologist.rsb.org.uk/biologist-features/everlasting-life-the-immortal-jellyfish
