Asteroids (sea stars) Ophiuroids (brittle stars) Sieve plate, also known as madreporite is a place on the organism by which waters gains entrance into the internal cavity of the organism. In sea stars, the sieve plate is situated on the aboral surface or the top surface. In brittle stars, the sieve plate is situated on the oral or the bottom surface. Body structure: In asteroids, the disk of the organism and its arms are more confluent to each other. The cavity between the disk and the arm is more open. In ophiuroids, the disk and arms are sharply set from each other. The arms are distinctly separated from the arms The support sturts, called anbulacrals are internal ossicles which form a raft like formation. The support structures are modified like vertebrae. Asteroids (sea stars) Ophiuroids (brittle stars) Sieve plate, also known as madreporite is a place on the organism by which waters gains entrance into the internal cavity of the organism. In sea stars, the sieve plate is situated on the aboral surface or the top surface. In brittle stars, the sieve plate is situated on the oral or the bottom surface. Body structure: In asteroids, the disk of the organism and its arms are more confluent to each other. The cavity between the disk and the arm is more open. In ophiuroids, the disk and arms are sharply set from each other. The arms are distinctly separated from the arms The support sturts, called anbulacrals are internal ossicles which form a raft like formation. The support structures are modified like vertebrae. Solution Asteroids (sea stars) Ophiuroids (brittle stars) Sieve plate, also known as madreporite is a place on the organism by which waters gains entrance into the internal cavity of the organism. In sea stars, the sieve plate is situated on the aboral surface or the top surface. In brittle stars, the sieve plate is situated on the oral or the bottom surface. Body structure: In asteroids, the disk of the organism and its arms are more confluent to each other. The cavity between the disk and the arm is more open. In ophiuroids, the disk and arms are sharply set from each other. The arms are distinctly separated from the arms The support sturts, called anbulacrals are internal ossicles which form a raft like formation. The support structures are modified like vertebrae. Asteroids (sea stars) Ophiuroids (brittle stars) Sieve plate, also known as madreporite is a place on the organism by which waters gains entrance into the internal cavity of the organism. In sea stars, the sieve plate is situated on the aboral surface or the top surface. In brittle stars, the sieve plate is situated on the oral or the bottom surface. Body structure: In asteroids, the disk of the organism and its arms are more confluent to each other. The cavity between the disk and the arm is more open. In ophiuroids, the disk and arms are sharply set from each other. The arms are distinctly separated from the arms The support sturts, called anbulacrals are internal os.