How Does a Chick Hatch?
Egg Tooth During embryonic development, a spike forms on the beak of a chick either at the tip or on the upper side of the beak. This spike looks something like a small tooth and is called the egg tooth. In chicken eggs, it must develop prior to the nineteenth day of gestation since they break into the air sac at that time. They must break into the air sac because the pores in the eggshell no longer allow enough oxygen transfer for them to breathe. They will be hatching very soon at 21 days gestation. The egg tooth disappears by the time the chick is two weeks old. Pipping Muscle Chicks are equipped during gestation with a special muscle on the back of their necks called a pipping muscle. The strength of the pipping muscle enables the fragile chick to beat against the hard calcium carbonate eggshell for hours until it finally breaks through and eventually emerges. Initially, this large neck muscle contracts to force the chick’s egg tooth through the egg’s inner membrane to access the a
