In Greek mythology, the Lernaean Hydra (Greek: Λερναία Ὓδρα) was an ancient serpent-like water monster with reptilian traits. It possessed many heads — the poets mention more heads than the vase-painters could paint — and for each head cut off it grew two more. It had poisonous breath and blood so virulent that even its tracks were deadly. The Hydra of Lerna was killed by Heracles as the second of his Twelve Labours. Its lair was the lake of Lerna in the Argolid, though archaeology has borne out the myth that the sacred site was older even than the Mycenaean city of Argos since Lerna was the site of the myth of the Danaids. Beneath the waters was an entrance to the Underworld, and the Hydra was its guardian. The Hydra was one of the offsprings of Typhon and Echidna (Theogony, 313), both of whom were noisome offspring of the earth goddess Gaia. Eurystheus sent Heracles to slay the Hydra, which Hera had raised just to slay Heracles. Upon reaching the swamp near Lake Lerna...