Monday, October 13, 2008

Strange and Terrifying Lake Monster

The hydra is a tentacled, neurotoxin-laden, self-regenerating, biologically immortal fresh-water predatory beast. All of which would be fairly terrifying to swimmers and water skiers -- if hydra weren't so small (1 millimeter contracted, fits comfortably on the head of a pin).

As it is, this remarkable creature barely arouses suspicion. If you live near a lake or pond you can catch some today. You can keep them in an aquarium. Someday you can tell your grandkids you, like Hercules, faced the hydra, one of the world's most bizarre, magnificent creatures.

There are many species under the genus Hydra. They enjoy a variety of wonderful names from the self-doubting (Hydra minima) to the ostentatiously patriotic (Hydra americana). Among other things, they share two peculiar properties: morphallaxis and biological immortality.

Morphallaxis is the ability to regenerate tissue. Remarkably, a hydra can be severed in two, and each half will produce a new hydra.

Possibly unique in the natural world, hydra apparently don't age. They defy senescence, the combination of deteriorating processes that lead to biological mortality in all other animals. From the 1998 Daniel E. Martinez paper abstract:
To test for the presence or absence of aging in hydra, mortality and reproductive rates for three hydra cohorts have been analyzed for a period of four years. The results provide no evidence for aging in hydra: mortality rates have remained extremely low and there are no apparent signs of decline in reproductive rates. Hydra may have indeed escaped senescence and may be potentially immortal.
Lakes and ponds are teeming with great champions of evolution. It's worth remembering the hydra, self-healing immortal.

(image credit: