Cnidarians are classified into four main groups: Anthozoa, Cubozoa, Scyphozoa, and Hydrozoa. There are about 10,000 species of Cnidarians. Cnidaria do not have organs like the heart and the lungs. They have an internal cavity for respiration and a gastrovascular cavity (a "stomach"). They possess a body wall made from two layers (the ectoderm and the endoderm) separated by a jelly-like layer called the mesoglea. All Cnidarians are radially symmetrical.
Examples: Jellyfish, Coral (Coral are sessile, which means that they don't move)
Examples: Jellyfish, Coral (Coral are sessile, which means that they don't move)