Sea stars have a light-sensitive region at the tip of each arm, but not a centralized nervous system to sustain actual eyes. The “tube feet” which you would feel on your arm would feel like suction if the animal were allowed to be submerged in sea water along with your arm. They use their water vascular system to create a vacuum and subsequently release the hydrostatic pressure. They can open oysters this way. I don’t know about throwing sand on their back. Seems that they wouldn’t mind too much, as they actually have endoskeletons (although it doesn’t seem like it). That’s because their skeleton is of mesodermal origin, and they have an epidermis on top of that. Hope I helped.

Sea stars don’t have pincers. They have tube-feet. If you put sand on their backs, it simply falls off. They have an exoskelton that can be slightly rough or very spiny.

If you live near one, I suggest visiting a public aquarium, like the one in Atlanta, GA or Monterey, CA. Orlando has SeaWorld, which is wonderful, too.

I know that this is not a direct answer to your question but might help you out…

Why not call a local aquarium? They may have “sea star” (Starfish) that you can go observe and possibly touch. I know many aquariums now have ‘touch tanks’ where you can actually touch starfish and the like.

Starfish are really hard (exoskeleton). They have tiny holes where little feelers like are. I honestly don’t remember what they feel like – but they help with mobility.

I honestly am 99.9% sure that they do not have eyes.

http://en.wikipedia.org/wiki/Starfish

You will find everything you need here including where the eyes are located.