This Little Animal Can Potentially Live Forever

Immortal hydra

Immortality, much? Scientists believe that the hydra may be able to eternally resist going gentle into that good night.

The Hydra of Greek myth was a terrifying many-headed water monster with virulent breath and noxious blood. And it was a creature with the wonderfully weird regenerative trait of being able to grow more heads when one was chopped off. Meanwhile, over in the pond, we have a genus of real-life little animals that share their name with the Greek horror show. And while they have the beast's regenerative powers in common, unlike the Hydra who was slain by Heracles, the little wiggly pond hydra appear to be immortal.

Belonging to the phylum Cnidaria, hydra are part of a group of organisms known as cnidarians which include jellyfish and sea anemones. And even though hydra are wee little multicellular organisms of less than half an inch in length, they are marvels of the animal world.

They feed on small aquatic invertebrates; they stick to surfaces with their single adhesive foot and hunt by somersaulting. They bend over and grab the surface with their mouth and tentacles, release the foot, and the body swings around to a new place where they re-attach their foot. Total little acrobats. And though not speedy, this alots them several inches of travel a day. When they attack their prey, they wrap it in their tentacles and can devour it in about 10 minutes; they are able to extend their body walls more than twice their size to consume meals larger than they are.

However, back to the immortality business. By all appearances, they seem to neither age nor die of old age. How can an animal not age? Radiolab's Robert Krulwich wonders the same and asks, why the hydra? "If nonsenescence, or biological immortality, is an option in nature, how come this particular mini-bit of pond scum got the big prize?" he muses, "Why not (excuse me for asking), us? Evolution is such a random, casino-like affair."