Would cephalization be an advantage to jellyfish? why or why not?

Cephalization does not confer an advantage to free-floating or sea organisms. Many aquatic species display radial symmetry like the jelly fish for instance.

Aquatic animals are not cephalized because they must be able to find food, take caution and defend themselves from harm from all directions.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).