corals  and    sea anemones ), Class Hydrozoa (   hydrozoans ), Subphylum Medusozoa: Class Cubozoa (   box jellyfish ), Class Scyphozoa (   jellyfish ), and Class Staurozoa which contains Order Stauromedusae (   stalked jellyfish ). Phylum Cnidaria may also contain  Family Polypodiidae  and  Family Tetraplatidae . Species