When the Time Lords of Doctor Who face a fatal blow, they can always regenerate, taking on a newer, and often younger, body. A certain species of hydrozoa can perform a similar trick, going into hibernation when times are tough and then emerging as a younger version of itself. And researchers say this potentially immortal creature is slowly taking over our seas.
The jellyfish-like hydrozoan, Turritopsis dohrnii survives through a phoenix-like ability. When faced with a food shortage or environmental danger, the T. dohrnii collapses into a blob and starts its lifecycle all over again. Not only have researchers deemed the organism “nearly immortal,” this phoenix property has enabled the T. dohrnii to spread to oceans all across the globe. Passing ships frequently swallow up the hydrozoa in their ballasts, triggering the rejuvenation process. Thus, an adult hydrozoan that has already reproduced could be swallowed up and dropped off elsewhere to restart its lifecycle and reproduce all over again.
Thus far, researchers have not found that the T. dohrnii, which can be identified only through genetic testing, have upset any of the ecosystems they have invaded. But the predatory creatures seem to be the perfect alien invaders: difficult to detect, patient, and successful in the face of adversity.