Sea Urchins and Sand Dollars (Class Echinoidea) are Echinoderms that have lost their five legs. However, the radial symmetry with five parts is still present in these species.

Starfish group (Phylum Echinoderma) contains some diverse marine creatures. Echinoderms generally have radial symmetry. Some well-known examples of Echinoderms are starfish and sea urchins. There are about 6,000 extant species of Echinoderms (and many additional fossil species). The following classes are contained in this phylum:

   Echinodea:       Sea Urchins (900 species)
   Asteroidea:      Starfish (1,600 species)
   Holothurioidea:  Sea Cucumbers (900 species)
   Ophiuroidea:     Brittle Stars (2,000 species)
   Crinoidea:       Feather Stars and Sea Lilies (600 species)

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.