Editing Digestion (section)

====Beaks====
[[Bird]]s have bony [[beak]]s that are specialised according to the bird's [[ecological niche]]. For example, [[macaw]]s primarily eat seeds, nuts, and fruit, using their beaks to open even the toughest seed. First they scratch a thin line with the sharp point of the beak, then they shear the seed open with the sides of the beak.

The mouth of the [[squid]] is equipped with a sharp horny beak mainly made of cross-linked [[proteins]]. It is used to kill and tear prey into manageable pieces. The beak is very robust, but does not contain any minerals, unlike the teeth and jaws of many other organisms, including marine species.<ref name=Miserez>{{cite journal |last=Miserez|first=A|author2=Li, Y |author3=Waite, H |author4= Zok, F  |year=2007|title=Jumbo squid beaks: Inspiration for design of robust organic composites |journal=[[Acta Biomaterialia]] |volume=3 |issue= 1|pages=139–149 |doi=10.1016/j.actbio.2006.09.004 |pmid=17113369 }}</ref> The beak is the only indigestible part of the squid.