This occurs because it minimizes the polar non polar interactions that we have here. It releases the water molecules and that stabilizes the interactions that now can exist between the water molecules and other water molecules and these heads. So it allows the polar heads to interact with water as well as with each other and it also basically hides these hydrophobic regions on the interior and allows them to interact with each other. And this is what we call the hydrophobic effect. So in the same way that it's the hydrophobic effect that allows the protein structure to basically form into its three dimensional shape and it's the hydrophobic effect that allows the nucleic acids to basically aggregate and form the double helix of DNA. It's the hydrophobic effect that is the driving force of the formation of the MyCell structure as well as of the bimolecular sheet, the lipid bilayer.