Question

What is the chief difference between the hydrozoans and the rest of the cnidarians regarding the germinal layer(s) in which its 'defensive structures or cells of defence' occur?

Answer 1

Answer:

Explanation:

These features distinguish hydrozoans from other cnidarians regarding germinal layers:

• Nematocysts are only in the epidermis

• Gametes are epidermal and released to the outside of the body rather than into the gastrovascular cavity

• And Mesoglea is largely a cellular.

• Medusa projects inward to form a Shellie lip, called the vellum. A vellum is present on most hydrozoan medusae but is absent in all other cnidarian classes.