The Immortal Jellyfish | Olivia Lu | TEDxDanube Intl School Vienna Youth

The immortal jellyfish, scientifically known as *Turritopsis dohrnii*, is a creature capable of reversing its aging process, a feat previously considered science fiction. Unlike most multicellular organisms that follow a linear life cycle of birth, growth, reproduction, decline, and death, this small jellyfish can revert to its earliest form. Beginning as a microscopic larva called a planula, it develops into a polyp attached to the seafloor. From this polyp, juvenile jellyfish, or medusae, bud off and mature. While most jellyfish die when they age, become injured, or face environmental stress, the immortal jellyfish has a unique survival mechanism called transdifferentiation. This remarkable cellular process allows fully developed cells, like nerve or muscle cells, to transform into different cell types. When faced with adverse conditions, the jellyfish shrinks its bell, retracts its tentacles, and collapses its body. Its cells then reorganize, forming new tissues and reverting the organism back to its polyp stage. This effectively acts as a biological reset, allowing the jellyfish to become young again and repeat its life cycle indefinitely. Scientists are studying this process, noting the activation of genes related to stem cells, cellular repair, and regeneration. While the jellyfish isn't truly immortal in the sense that it can still be eaten or harmed, its ability to reverse biological age challenges our understanding of life and death. This insight, coming from an organism without a brain, suggests that time and aging are more flexible than we previously imagined. The study of this creature could lead to advancements in how we approach aging, recovery, and disease, promoting longer, healthier, and more resilient lives. Ultimately, the immortal jellyfish offers a powerful lesson about renewal, repair, and the possibility of new beginnings, demonstrating that endings are not always final and that life can always find a way to start again.