The hydra is a type of dragon, which has more than one head. There are stories about multi-headed dragons all around the world, including Japan and Greece. In Greek mythology the Hydra is a many headed water snake that lives in a swamp. It’s parents were Typhon and Echidna.
If you cut off one of a Hydra’s heads, it will grow back again; this made it very hard to fight and defeat. In Greek mythology, one of the Hydra’s heads was immortal. Some Hydras also have additional tails, wings or arms. Apart from these extra limbs, they can also look like another type of dragon. It got it’s name from the Greek word for water.
Hercules was set twelve challenges and one of them was to defeat Hydra. Hercules went to Hydra and tried to kill him. He cut off all of Hydra’s heads and burned them. When he cut off one of the heads it kept on coming back to life. So Hercules crushed that head and buried it and he succeeded in killing Hydra.