I know the egg tooth is used by a chick to break out of the actual shell, but does it have any other purposes?
Andy Cawthray says:
The ‘egg tooth’ is a small, sharp temporary cap that sits on the end of the beak of a chick. It develops whilst the chick is within the egg and has two key uses. The first is to help the chick break into the air sac within the egg. Egg shells are porous and allow the movement of oxygen into an egg but towards the end of the incubation period this flow of air is insufficient. The chick, using its egg tooth, will then break through the membrane of the egg and into the air sac where sufficient oxygen can be found. It is then the more commonly known function of the’ tooth’ comes into play during pipping which is when the chick uses it to break out of the shell.