Hydra' comes from the Greek word 'Hydra', meaning 'water snake'. Therefore, biologists use it to classify a water-based species with characteristic tentacles at the end of a tube-like body. Apart from this, the English dictionary also incorporates the phrase 'hydra-headed.' The phrase refers to a difficult situation with multiple aspects to consider. The phrase is derived from the mythical monster slain by Heracles as part of his labors to atone for the sin of killing his wife and child due to his stepmother's insanity.