On which surface of a starfish suckers visible?

The suckers of a starfish are visible on the oral surface of the starfish. The oral surface is the side of the starfish that has the mouth and most of the other sensory organs. This side of the starfish is also where the starfish's tube feet are located. The tube feet are small, cylindrical appendages that are used for locomotion and feeding. Each tube foot has a suction cup at the end of it, which allows the starfish to attach to surfaces.