A mythical monster of ancient Greece, the Lernean Hydra was a serpent with many heads— usually nine. Each time a head was cut off, two more grew in its place. It was finally killed by Heracles after he cauterized the Hydra’s neck stumps with fire after each decapitation.
The Hydra was a water monster that lived in a cave near the lake of Lerna is Eastern Greece. Beneath the lake was an entrance to the Underworld, and the Hydra guarded it. Its breath was foul and its blood was poisonous.
The Hydra had many heads: traditionally, it had nine, but some sources list as many as 50 heads. Every time a head was cut off, two more grew in its place, making it nearly impossible to kill.
The hero Heracles was tasked with killing the Hydra by King Eurystheus, an agent of the goddess Hera, who created the Hydra with the express purpose of killing Heracles.
Heracles tried to kill the Hydra by cutting off its heads, but was getting nowhere. It wasn’t until he started sealing the fresh wounds with a firebrand to keep new heads from growing that he succeeded in cutting off all its heads.
For good measure, Heracles dipped his arrows in the Hydra’s blood, making them poisonous.
Curlee, Lynn. Mythological creatures: a classical bestiary : tales of strange beings, fabulous creatures, fearsome beasts, & hideous monsters from ancient Greek mythology. New York: Atheneum Books for Young Readers, 2008. Print.
Nardo, Don. The monsters and creatures of Greek mythology. Mankato, MN: Compass Point Books, 2012. Print