Polyzoa

Part of speech: noun

Definitions

1. Colonial aquatic invertebrate animals that form branching or encrusting colonies, each made of tiny individual zooids housed in protective cases
2. Small sessile filter-feeding animals living in colonies on the seabed, rocks and seaweed, often mistaken for corals or moss
3. A group of microscopic colonial marine creatures that build calcareous or horny skeletons and feed by means of a crown of tentacles

Etymology: "Polyzoa" is the plural of "polyzoon," a compound built from two Greek elements: "polús," meaning "many," and "zoon," meaning "animal." Together they name a group of tiny aquatic animals that live in colonies, each individual being a minute creature that secretes a shared or separate protective casing. The name describes the basic fact about them: many animals gathered into one structure. The plural form is what English uses for the whole group, so "polyzoa" refers to the colonial animals collectively, while "polyzoon" refers to a single member. The first element, "poly-", appears throughout scientific English in words like "polygon" and "polyglot," always carrying the sense of "many." The second element, "-zoon," is the same Greek word found in "zoology" and "protozoa," and it is the root behind the Greek word for "animal" generally.

Synonyms: bryozoans, moss animals