BIOL 2030 Chapter Notes - Chapter 14: Tube Feet, Radial Nerve, Endoskeleton
Document Summary
Often called starfishes, demonstrate basic features of echinoderm structure and function. The band from which the tube feet (podia) project is called an ambulacrum, it extends from the mouth along the oral sides of each arm to its tip. Ambulacral groove occurs along the middle of each ambulacrum and contains rows of tube feet (bordered by movable spines). Large radial nerve can be seen in the center of each ambulacral groove between the rows of tube feet. Under nerve is an extension of the coelom and the radial canal of the water-vascular system. Ossicles or other dermal tissue cover these structures (except in crinoids) therefore ambulacral grooves are closed: aboral side . Rough and spiny (spines flattened so surface appears smooth) Around bases of spines in many sea stars are groups of minute, pincerlike pedicellariae, bearing tiny jaws manipulated by muscles. Jaws keep body surface free of debris, protect papulae and sometimes aid in food capturing.
