Jellyfish are among the ocean’s most incredible inhabitants, boasting a wide array of forms and ... [+]
Despite advances in biological science, the ocean remains shrouded in mystery, teeming with creatures that defy human understanding and challenge the limits of our imagination. Among these marine marvels are jellyfish.
These creatures, which have inhabited Earth’s oceans for millions of years, showcase a diversity that ranges from the eerily beautiful to the outright alien. From the ghostly glow of bioluminescent species like Aequorea victoria to the towering tentacles of the lion’s mane jellyfish, each species reveals a unique facet of nature’s ability to adapt and evolve.
A closeup shot of a glowing blue jellyfish in black water.
One species stands out for its extraordinary ability: Turritopsis dohrnii, also known as the immortal jellyfish. This fingernail-sized, unassuming creature possesses the rare ability to revert back to its juvenile polyp stage after reaching maturity, which is an early stage in the life cycle of a jellyfish, when they typically attach themselves to the seafloor or another solid surface.
During this phase, the jellyfish resembles a small stalk with tentacles that reach upwards, capturing food particles from the water. Polyps can reproduce asexually, budding off new polyps to colonize an area. This stage is crucial in the jellyfish lifecycle, serving as a foundation for individual jellyfish to later develop into their free-swimming, mature form known as the medusa.
Essentially, when faced with stress, injury or old age, the immortal jellyfish can transform all of its existing cells into a younger state. This process, known as transdifferentiation, allows it to cycle back to the beginning of its life, potentially indefinitely, offering it a unique form of biological immortality. Through this remarkable mechanism, Turritopsis dohrnii challenges our understanding of life cycles and aging.
How Do These Jellies Bypass Traditional Aging Processes?
Scientists have successfully mapped the genome of Turritopsis dohrnii, revealing a complex genetic blueprint that rivals other similar species in detail and quality. This extensive genetic map, encompassing roughly 400 million base pairs, matches closely with previous estimates and introduces a wealth of genes—over 20,000 in total—that may hold the key to its unique ability to revert to a juvenile state and potentially live forever, according to two articles published in 2022 in Proceedings of the National Academy of Sciences and DNA Research.
The genetic instructions uncovered in the Turritopsis dohrnii genome include sequences that dictate when and how cells should perform transdifferentiation. Specifically:
- Gene activation. Certain genes within the Turritopsis dohrnii genome become activated when the jellyfish encounters stress, injury or reaches old age. These genes signal the cells to initiate transdifferentiation.
- Cell transformation. During transdifferentiation, mature cells in the jellyfish’s body change their form and function, effectively turning into different types of younger cells that would make up a juvenile polyp. This transformation involves altering the expression of numerous genes, turning some on and others off, to revert the cells to a state where they can divide and grow anew.
- Regeneration and reversion. The transformed cells then work together to reconstruct the jellyfish’s body into the polyp stage.
The genome mapping provides a detailed look at the genes involved in this process and how they are regulated. By comparing these genes and their functions to those in organisms that age in a more standard manner, scientists hope to identify the mechanisms that allow Turritopsis dohrnii to escape the usual fate of senescence, the loss of a cells ability to grow and divide.
So, The Oldest Living Animal Has To Be The ‘Immortal’ Jellyfish, Right?
Despite the immortal jellyfish’s incredible ability to potentially live forever, claiming it as the oldest living animal is tricky. Out in the vast, wild ocean, they can die due to events like predation and environmental changes. Plus, studying these tiny creatures in their natural, expansive habitat proves immensely challenging, leaving us without concrete evidence of their longevity in the wild.
Even if these jellyfish are unable to actually live forever, learning about this jellyfish’s unique ability holds promise not just for understanding the mysteries of the deep but for advancing regenerative medicine and exploring anti-aging solutions in humans and other species, offering a glimpse into a future where the boundaries of life may be extended.
