The beak of the squid baffles scientists. They wonder: How can something that is so hard be attached to a body that has no bones? Should not the combination of materials cause abrasion and hurt the squid.
         The tip of the squid’s beak is hard, whereas the base of the beak is soft. The composition of the beak –which is made up of chitin, water, and protein –changes in density so gradually from soft to hard that the squid can use its beak without causing any harmful abrasion.
         Professor Frank Zok, at the University of California, says that studying the squid’s beak could revolutionize the way engineers think about attaching materials together in all sorts of applications. One potential application is in the making of prosthetic limbs. Ali Miserez, a researcher at the same University, imagines creating a full prosthesis that mimics the chemistry of the beak, so that it matches the elasticity of cartilage on one side and, on the other side, is made of a material which is very stiff and abrasion resistant.