HYDRA, Lernaean Hydra (gr. Lernaĩos hýdra)
in Greek mythology the water monster (compare greek hýdōr „water”), offspring of ➚ Typhon and ➚ Echidna (I), brought up by ➚ Hera . Hydra dwelled under the plane-tree  at the swamp area near Lerna (Argolid), where it ravaged the fields and preyed on cattle. Hydra had nine heads, one of them immortal  and golden . The number of heads vary in different sources, reaching as many as one hundred .
Slaying Hydra was one of the labours of ➚ Heracles, who set out for it accompanied by his nephew ➚ Iolaus. Heracles scared Hydra away from its lair with flaming arrows and attempted to cut its heads off. In the place of every severed head a pair of new heads instantly grew. Gigantic crab ➚ Carcinus rushed to help Hydra and wounded the Heracles’ heel. The ➚ hero killed the unexpected enemy and called Iolaus to come to his aid. Hero’s companion set the neighbouring grove on fire and every time Hydra was decapitated, he burned the neck stump with a firebrand to prevent the regrowth. Eventually Heracles managed to cut off the immortal head and crushed it under a boulder. Then he split the corpse and poisoned his arrows with the monster’s bile. ➚ Eurystheus did not accept the killing of the monster because Heracles did not perform the job alone .
 H e s., Theog., 326 ff.;  P a u s., II, 37, 4;  A p d., II, 5, 2;  P t o l. H e p h., 147 b;  E u r i p., Her. fur., 1118.