How long does the immortal jellyfish live?
Potentially forever. Which gets more impressive considering these creatures have been floating through the oceans long before the dinosaurs went extinct (66 million years ago) – it's biologically possible for a single immortal jellyfish to have been alive for this entire time.
However, while this is technically feasible, it's by no means provable. That’s because these jellyfish have only been studied sporadically since the early 1980s, meaning experts have only a few decades’ worth of data.
There’s also another factor to consider. While an immortal jellyfish can age in reverse, it can also be easily killed by predators including various fish, sharks, turtles and even other jellyfish. This is why the immortal jellyfish is unlikely to overpopulate the Earth anytime soon
