Constellation Hydra Mythology

Hydra was a nine-headed monster in the form of a long, writhing water snake. Itattacked, killed and ate anyone who ventured near its swampy abode in Lernea. To slay this beast was the second of Hercules's twelve labors. This was a difficult task, since every time Hercules succeeded in cutting off one of Hydra's heads, two would grow back. Hera, who had always been resentful of Hercules, sent a giant crab to nip and bite at his feet as he attempted to slay the monster. He finally achieved this after telling his nephew, Iolaus, to burn each neck stump immediately after he severed the head preventing any regrowth.