Behold the humble water flea, locked in a battle of mythological proportions

In Greek mythology, Hydra was a monstrous water serpent that lived in a swamp and terrorized nearby residents. When intrepid Hercules sliced off one of Hydra’s multiple heads, two more heads grew back in its place. This counterintuitive result — when an action taken to reduce a problem actually multiplies it — is known as a hydra effect.