Echinoderms Aquatic Animals )Zoo-521) Jawaher Al-Zahrani

Order: Clypeasteroide Scientific Classification Kingdom: Animalia Phylum: Echinodermata Subphylum: Asterozoa Class: Asteroidea Class: Holothuroidea Class: Echinoidea Order: Clypeasteroide

Star Fish 1-Sea star or star fish are characterized by radial symmetry, several arms (5 or multiplied by 5) radiating from a central body. 2-Mouth on the underside , the anus is at the center of the disc together with the water intake (madreporite) on the top. 3- The upper surface is often very colorful. There are cilia like structures that ensure that the surface of the arms stay free from algae.

Sea cucumber 1-They do not have distinct radial symmetry but are bilateral with a distinct dorsal and ventral part. 2-They have a leathery , elongated, muscular , flexible body with a mouth at one end the anus at the other end. 3-Around the mouth there is a number of tentacles (modified tube feet) used in food collecting.

Sand dollar 1-The sand dollar is a spiny , hard-skinned animal that is shaped like a coin. 2-Sand dollars have 5-part radial symmetry. 3-It has a hard skin made of calcium carbonate plates. 4-The bottom surface contains the mouth, many black spines (which trap food), and the cilia (small) hairs that help direct food into the mouth. 5- Sand Dollars have tiny tube feet that are used as gills. 6- The holes on the top surface are where the eggs and sperm are released.