What does polyzoan mean?
A polyzoan is a tiny marine or freshwater invertebrate traditionally associated with the phylum Polyzoa and now generally called a bryozoan. Polyzoans rarely live alone: each is one zooid in a colony whose members are connected and may share a protective skeleton. Their feeding structures can be withdrawn into the colony when disturbed, making the colonies resemble small plants, crusts, or branching fans. The word can name an individual animal, although individual zooids are often difficult to distinguish from the colony as a whole. It is also used attributively in terms such as polyzoan colony and polyzoan fossil. The word has largely yielded to bryozoan in contemporary biological usage, but it remains valuable in historical, palaeontological, and specialist contexts. Its unusual history reflects an older zoological name built from Greek roots meaning “many” and “animal,” appropriate for colonies composed of numerous cooperating units.
A bryozoan, especially an individual zooid forming part of a larger colony.
"The diver noticed a polyzoan growing on the dark side of the wreck."
Also historically used as a member of the former phylum Polyzoa; bryozoan is the usual modern term.
Relating to bryozoans or characteristic of a bryozoan colony.
"Researchers identified the fossil as a polyzoan colony preserved in fine-grained limestone."
Common in specialist and historical writing, especially in the expression polyzoan colony.
The plural is used for individual members of the group; a whole interconnected community is generally called a polyzoan colony.
"Several polyzoans were visible around the edges of the coral."
A single polyzoan is microscopic, but thousands can cooperate in a colony that looks like a plant, a crust, or delicate underwater lace.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does polyzoan come from?
Polyzoan combines the combining form poly-, from Greek polus, “many,” with -zoan, from Greek zōion, “animal” or “living creature.” The name reflects the colonial organization of bryozoans, whose numerous zooids are connected to form a single integrated structure. The taxonomic name Polyzoa is no longer generally preferred, and modern English usually uses bryozoan, from the same Greek animal root.
Related word forms
How polyzoan is actually used
The term is chiefly zoological and formal. In modern classification, bryozoan is more widely used, while polyzoan remains common in older literature and in the compound form polyzoan colony.
Easily confused with polyzoan
Polyzoa is a former taxonomic name for the bryozoan group, whereas a polyzoan is an individual member of that group.