Hydra

The Hydra was the sister of the Nemean lion and Euristio chose it as the subject of the second work of Heracles, knowing that the hydra wanted to avenge the death of the beast. Heracles left Tiryns wearing on his head, lion's mane and shouted Euristio leave his trophies out of town. Heracles ignored and left accompanied by his nephew Iolaus.

The people of Lerna for Drinking water should pass in front of the lair of the Hydra. Many died devoured by the monster's mouths with the help of the crab Cancer.

When Heracles came to the lair of the Hydra, heads began to tell, but for every severed head stuck out two. They sought help from Iolaus cauterized the necks and when only the central head was cut off and buried under a large stone that can be seen on the outskirts of Lerna.

Heracles dipped his arrows in the poisoned blood of the Hydra and returned to Tiryns.

Eurystheus did not recognize the work of Heracles because he had helped Yoalo.