What do octopus use there tentacle's for?

They use their arms to grasp onto pray..... and to hold on to rocks or and object wile it moves, and octopuses are extremly curious.... when scientists put a can in an aquarium with one they dicovered that it put it on its head for shelter and when the but a jar with food inside and a lid on top the octopus opened the jar to get to the food so they alo discovered that the octopuses intelagence.