This creates an opening between the two shells that is only .01 inches wide. Using this tiny gap, the sea star then puts its stomach into the clam's shell . Once this happens, the mussel or clam dies. When it is done, nothing is left but an empty shell. These creatures have many sharp spines pointing out in all directions that offer protection from predators.
Spines are able to swivel towards a predator because they are connected to muscles.
This group has five paired rows of tube feet with suckers. The mouth is on the bottom, and the anus on top. The mouth contain five teeth that point towards the center. The tubed feet are used to move along the bottom of the sea, where these organisms use their teeth to eat algae. Sea Cucumbers Sea cucumbers belong to a sub-category of echinoderms called holothuroidea.