Immortal Jellyfish Reverts Age

In the vastness of the ocean, a remarkable creature defies the conventional cycle of life and death. The *Turritopsis dohrnii* jellyfish, a tiny organism roughly the size of a human pinky nail with a transparent bell and a distinctive red stomach, possesses an extraordinary capacity to rejuvenate itself. Instead of succumbing to old age or injury, this unique animal can effectively hit a "reset" button on its life, transforming back to an earlier, juvenile stage.

This incredible feat is achieved through a biological process known as transdifferentiation. When faced with environmental stress, physical damage, or even the natural process of aging, the adult jellyfish can revert its specialized cells—such as muscle or nerve cells—into a less differentiated state. These reprogrammed cells then form a new colony of polyps, which are the juvenile stage of the jellyfish life cycle. From these polyps, new, genetically identical jellyfish emerge, effectively restarting their lives. This process can theoretically repeat indefinitely, granting the *Turritopsis dohrnii* biological immortality.

While the species was first discovered in the Mediterranean Sea in 1883 (Review), its astonishing ability to reverse its life cycle was not observed until the 1990s. Scientists like Giorgio Bavestrello and Christian Sommer were among those who recognized this phenomenon, sparking immense scientific interest. Researchers are now intensely studying the *Turritopsis dohrnii*'s genetic makeup and cellular mechanisms to unlock the secrets behind its rejuvenation. Insights from this "immortal jellyfish" hold significant promise for fields such as stem cell biology and regenerative medicine, offering potential avenues for understanding and combating aging and disease in other organisms, including humans.