hydrozoa

/ˌhaɪdrəˈzoʊə/
noun
  1. A class of small, simple animals that live in water, including hydras and some jellyfish. They are related to corals and sea anemones.
    • The Portuguese man o' war is a well-known colony of hydrozoa that looks like a single jellyfish.
    • Many hydrozoa have a life cycle that includes both a polyp stage and a medusa stage.
    • In biology class, we studied how hydrozoa reproduce both sexually and asexually.
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