What does hydrozoan mean?
A hydrozoan is a member of the class Hydrozoa, a major group within the cnidarians, the animals that include jellyfish, sea anemones, and corals. Hydrozoans are best known for their life cycles, which commonly alternate between a sessile polyp form and a free-swimming medusa form, although the two stages are not equally developed in every species. Many hydrozoans form colonies whose specialized zooids perform functions such as feeding, defense, and reproduction, making the colony both structurally complex and biologically unusual. The adjective hydrozoan describes these animals or anything associated with them, as in a hydrozoan colony or hydrozoan polyp. In specialized writing, the term carries no everyday figurative meaning: it identifies a particular branch of cnidarian biology rather than a general type of jellyfish.
A member of the class Hydrozoa, a group of mostly colonial cnidarians commonly exhibiting polyp and medusa stages.
"The newly discovered hydrozoan was found attached to a rocky ledge in deep water."
A technical zoological noun; the plural is hydrozoans.
Of, relating to, or characteristic of a hydrozoan or the class Hydrozoa.
"Scientists used genetic evidence to reconstruct the hydrozoan colony's evolutionary history."
Common in taxonomic and biological descriptions.
The standard plural of the noun hydrozoan.
"Several hydrozoans attach to the seabed and form branching colonies."
Some hydrozoans look like one animal; others are intricate floating colonies whose specialized members can even resemble tentacles.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does hydrozoan come from?
Hydrozoan combines the combining form hydro-, from Greek hudor, meaning “water,” with zo-, from Greek zōion, meaning “animal,” and the suffix -an, denoting a member. These elements also connect the word with English words such as hydrogen and hydrology on one side and zoology on the other.
How hydrozoan is actually used
This is a specialized zoological term used in marine biology, taxonomy, and discussions of cnidarian evolution. It is uncommon in general speech, and the noun is more specific than the broader term cnidarian.
Easily confused with hydrozoan
A hydroid more specifically refers to a colonial hydrozoan or its dominant polyp stage, whereas hydrozoan is the broader term for any member of Hydrozoa.
Hydrozoon is a less common synonym for a hydrozoan, while hydrozoan is also widely used as an adjective.
A hydra is a particular freshwater hydrozoan with a simple tubular body, whereas hydrozoan denotes the much broader class to which it belongs.