actually that's a very good question who ever aks this,and the function of the arm of a sea star is just to help the sea star to get food and it hepls to they can walk inside of the ocean
98.4% of them have 5 sections, PS. They will have four if you drag them out but in about a month a new section will grow... IMPROVEMENT:Oh, sorry, I forgot to say...Some of them can have up to 200