Does a hydrozoa have a Medusa stage?

Yes, hydrozoans typically have a Medusa stage in their life cycle, although not all species exhibit both forms. The life cycle usually includes both a polyp stage, which is sessile, and a Medusa stage, which is free-swimming. The Medusa stage is often bell-shaped and equipped with tentacles, allowing for reproduction and dispersal. However, some hydrozoans may remain in the polyp form throughout their life.