Microscope slide of spicules - Examine the spicules of Grantia . These consist of calcium carbonate. About 10,000 species of Cnidaria exist. All are aquatic and most are marine. These include the jellyfishes, corals, the sea anemones, and some other organisms.
Cnidarians have two forms.
Cnidarians reproduce both sexually and asexually, and individuals of some species spend part of their lives as a polyp and part as a medusa. Most cnidarians are predators that feed on zooplankton, but a few eat larger organisms, including fish. They obtain prey using their cnida, which are subcellular structures to spear and harpoon prey. The classes differ in structure and in the relative importance of the polyp versus medusa stage. Examination of specimens of Hydrozoa 2 a. Microscope slides of Hydra - This solitary freshwater Hydrozoan lives only as a polyp, which reproduces asexually by budding.