Athena told Herakles to force the monster from the swamp with fire arrows. He did, but the monster twisted itself about his feet. He beat the heads with his club, but crushing one head only caused others to erupt. A great crab crawled from the swamp to help the Hydra. It bit Herakles in the foot. He crushed its shell. Herakles called Iolaos for his help and cut the Hydra's heads off with his sword. Iolaos sealed the neck stumps with torches so other heads could not grow in their place. 