The animal widely considered to be biologically immortal, meaning it doesn't age in the traditional sense, is the Turritopsis dohrnii jellyfish.
This small jellyfish possesses an extraordinary ability called transdifferentiation. When faced with physical damage, stress, or starvation, instead of dying, it can revert back to its polyp stage. This polyp stage then forms a new jellyfish colony, essentially restarting the life cycle.
Here's a breakdown of the process:
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Normal Aging: Most animals progress through life stages, accumulating cellular damage and experiencing a decline in function over time, eventually leading to death.
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Transdifferentiation in Turritopsis dohrnii: When threatened, the adult jellyfish can transform all of its existing cells back into the polyp stage. This is not simply regeneration of lost limbs, but a complete cellular reversal.
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Polyp Colony Formation: The polyp stage is a colonial form, attaching to the seabed. This polyp then buds off new, genetically identical jellyfish.
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Immortality (with caveats): This process allows the jellyfish to theoretically avoid death from aging indefinitely. However, it's important to note:
- Predation and Disease: Turritopsis dohrnii is still susceptible to being eaten by predators or succumbing to diseases.
- Environmental Factors: Unfavorable environmental conditions can also kill the jellyfish.
- "Immortality" is conditional: It requires the triggering event (stress, damage) to initiate the reversion process. They don't always revert.
In essence, the Turritopsis dohrnii can circumvent the normal aging process by reverting to an earlier life stage, making it a unique and fascinating creature in the realm of biological immortality. While it's not invincible, its ability to cheat death through transdifferentiation sets it apart.
