Hydrozoa (hydrozoans) are a taxonomic class of very small, predatory animals which can be solitary or colonial and which mostly live in saltwater. A few genera within this class live in freshwater. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria.

Hydrozoa Encrusting a Small Shell

Hydrozoa (hydrozoans) are a taxonomic class of very small, predatory animals which can be solitary or…

"Fish, trilobites, brachiopods, corals, and graptolites of the Palaeozoic epoch." -Taylor, 1904

Paleozoic Animals

"Fish, trilobites, brachiopods, corals, and graptolites of the Palaeozoic epoch." -Taylor, 1904