The Class Hydrozoa is made up of organisms known as Hydrozoans. They are mostly colonial with a few exceptions. Hydrozoans that are colonial usually consist of two different kinds of poylps: the feeding polyp and the reproductive polyp. A feeding polyp captures food for the polyp and a reproductive polyp asexually reproduces hydrozoan medusae. Most hydrozoans alternate between a polyp and a medusa stage — they spend part of their lives as "jellyfish."