By Riona Merchant
It's one thing to survive in harsh environments, but quite another to hit the reset button when in an imminent threat.
Turritopsis dohrnii, a species of jellyfish initially found in the Mediterranean Sea in the 1880s, is the only animal known to possess this amazing ability. Turritopsis dohrnii, like all jellyfish, begins life as a larva called a planula that grows from a fertilized egg. A planula begins its life as a swimmer before landing on the ocean floor and developing into a polyp colony. These eventually give birth to free-swimming, genetically identical Medusae, which develop into adult jellyfish in a matter of weeks. Turritopsis dohrnil, when fully developed, measures only 4.5 mm (0.18 inches) across, or approximately the size of a pinky nail. Its clear bell is surrounded by up to 90 white tentacles, and in the centre is a bright-red stomach.
However, these small, transparent animals have a remarkable capacity for survival. They regress in their development and turn back into polyps in reaction to physical harm or even famine. The reborn polyp colony eventually blooms and releases medusae that are genetically identical to the damaged adult, in a process that remarkably resembles immortality. In fact, the species has earned the moniker "the immortal jellyfish" since this behavior was first noted in the 1990s. It is caused by a rare cellular process called transdifferentiation.
Scientists are particularly interested in it because of its possible medical uses. An adult cell that is specialised for a particular tissue might transform into a completely different kind of specialised cell by going through transdifferentiation. It is an efficient way of cell recycling and a crucial topic of investigation in stem cell research that could aid in the replacement of disease-damaged cells.
Sources:
https://www.amnh.org/explore/news-blogs/on-exhibit-posts/the-immortal-jellyfish
https://www.nhm.ac.uk/discover/immortal-jellyfish-secret-to-cheating-death.html https://www.nytimes.com/2012/12/02/magazine/can-a-jellyfish-unlock-the-secret ofimmortality.html https://a-z-animals.com/animals/immortal-jellyfish/
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