Starfish (also called sea stars) are really interesting animals. They have those tube feet that can stick to things. They can put their stomach inside out inside a clam shell. What they can’t do is regulate their salt and water balance. If the salinity changes too much, they have to leave or die.

They can’t regulate their body temperature either, except by their behavior. They can move to a warmer or cooler place. If they’re too cold, they can’t move very fast. If they get too hot, they eventually die.

Sea stars also have to stay wet. They can curl in their feet and slow down the drying-out process for a while, but they need to stay near water. That’s okay because their prey are in water anyway. The movement of the water can push them around if it’s really strong, but their tube feet are good at gripping the rocks, so small waves probably don’t bother them much.

What kind of senses do you think sea stars have to have to keep themselves out of trouble? You may want to study marine biology.

Starfish are extremely sensitive to tides and salinity. Clams, mussels, oysters, etc. can escape predation by starfish by living in environments where the starfish can't go.