Echin oderms
Starfish and sea urchins live in areas that vary from shallow to deep water. Their habitats change from rocky bottom, low tide line, and rocky shore. They sometimes live on land. Their food is anemones, sea cucumbers, and small snails.
They are very important to humans and their environment. They are used to study the beginning of all mollusks. They control seaweed growth and let coral grow. Small animals eat their larvae.
They are very unique animals. Some have forty arms or more. They cut off their arms in defense. Also, if they are cut in half they grow into two, separate starfish . There are many examples of this animal. One is the blood star. Another is the sunflower starfish and the blue starfish. A few more are the white starfish, the giant starfish and the sea star.
They have a central disc and arms for body construction. Their mouth is in the middle of their underside. They also have a bag-like stomach. They have tube feet for crawling and a jointed appearance.
They have a water vascular system and can exchange gasses directly in the water. The water goes in through their madreporite which goes through the stone canals. The water vascular system proves locomotion, respiration and feeding to the organisms.
They have yellow yolky eggs that stick together after fertilization. They live around 3 to 5 years, sometimes longer. They release their eggs into the water for reproduction.
  They sense light with colored eye spots at the tip of each arm. They have nerve cords, but they don't have a brain.
Waste goes through their anus on the top side of the body. They also have two stomachs, the cardiac and the pyloric. 
They take in food through their digestive glands and arms that go to the stomach.
Echinoderms are marine animals with a radiating arrangements of parts. Starfish also have a 5 part radial symmetry. 



 
Echnoidea is a class of starfish. They move by pivoting their long spines and are adapted for eating seaweed. Holothuroidea is another class of starfish. They don't have spines and they have a reduced endoskeleton. Astroidea have a central disc with broad based attachments, which is also their arms. The crinodea classes of echinoderms use their arms for suspension feeding. Ophiuroidea have long flexible arms and tube feet, but they lack suckers. They move by lashing their arms.

 
 
  
Starfish Video
User Name: wsr267
Password: aea267