The purpose is to demonstrate how some sea organisms, such as sea anemones, secure themselves to rocks.
Things Required:
Suction cup (the type used to secure hanging crafts to windows works well)
Rock
Directions:
Wet the suction cup and press it against the rock. Pick the rock up by holding onto the suction cup.
This Is What Happens:
The suction cup sticks so securely that the rock can be lifted.
Science Behind It:
Pressing the cup against the rock forces the air out of the cup. The water forms a seal around the outside preventing the air from re-entering the cup. The air in the room actually pushes with so much force on the outside of the cup that it is held tightly against the rock. The suction cups on sea anemones work the same way. Under the water, the suction cups on the organisms are held tightly against rocks by the pressure of the water.
