GENERAL HISTOLOGY

Detailed explanation-1: -Class Hydrozoa–the polyp phase is dominant and the medusa is reduced or absent from the life cycle. The symmetry is radial. This class includes the fire corals, hydroids, and siphonophores.

Detailed explanation-2: -Some examples of hydrozoans are the freshwater jelly (Craspedacusta sowerbyi), freshwater polyps (Hydra), Obelia, Portuguese man o’ war (Physalia physalis), chondrophores (Porpitidae), “air fern” (Sertularia argentea), and pink-hearted hydroids (Tubularia).

Detailed explanation-3: -The class hydrozoa is the most diverse class of cnidarians and includes siphonophores, hydroids, fire corals, and many free-swimming medusae species.

Detailed explanation-4: -The Hydrozoa are mostly marine predators that constitute a class in the Cnidaria, to which the corals and jellyfish also belong. Hydroids are a polyp life stage of most hydrozoans, which may be colonial.

Detailed explanation-5: -The Hydrozoa is a subgroup of cnidarians containging approximately 3700 species. It is a diverse group with a variety of life cycles, growth forms, and specialized structures. Like many cnidarians, hydrozoans have both polyp and medusa stages in their life cycle.