What does hydrozoan mean?

Hydrozoan refers to a class of small, predominantly marine animals within the phylum Cnidaria, which also includes jellyfish and corals. They are characterized by their polyp and medusa life stages, often exhibiting a colonial lifestyle. Hydrozoans can be found in various aquatic environments and are known for their diverse forms, including both solitary and colonial species. Examples include the common Portuguese man o' war and the hydra.