Constellation
Mythographers relate that the Lernaean Hydra and the crab were put into the sky after Heracles slew them. In an alternative version, Hera's crab was at the site to bite his feet and bother him, hoping to cause his death. Hera set it in the Zodiac to follow the Lion (Eratosthenes, Catasterismi). When the sun is in the sign of Cancer, the crab, the constellation Hydra has its head nearby.
Read more about this topic: Lernaean Hydra