water channels made up of eight different types of aquaporins.what is the meaning of this statement?

Aquaporins are the small proteins that form pores in the outer membranes of the plastids, mitochondria and some bacteria allowing molecules up to the size of small proteins to pass through. Water channels contain different types of aquaporins. Aquaporins allow in & out movement of water molecules & prevent the entry of other ions inside the membrane. The different porins present in the water channel have different pore size as a result they have affinity for different molecules.