We seldom see starfish from below. This video features the underside of a starfish at the National Aquarium in Baltimore. The starfish has dozens of tiny feet called podia. Scientist thought that these podia contain suckers that allow the starfish to cling to glass and other surfaces by a suction process. However, there is also evidence that the podia secrete sticky chemical substances that help the starfish attach to surfaces. The starfish can extend and retract these podia using water pressure generated inside its body through what is called a water-vascular system.