Friday Feathered Fact
As rare as hen’s teeth. This idiom refers to the fact that no birds have teeth. However, all baby birds (except the kiwis of New Zealand) have a handy “egg tooth”. This temporary deposit of calcium carbonate on the tip of the bird’s beak has a dual purpose. First, the chick punctures through to the air sac within the egg, which provides more oxygen for the struggling chick. Second, the egg tooth rubs and pushes through the harder egg shell, called “pipping”. These young birds also have a special “pipping muscle” on the back of the neck that provides more strength to push that little egg tooth against the shell. Lizards and snakes also have an egg tooth. Remarkably, the egg-laying mammals (platypus and echidnas) also have this same egg tooth to reach the outside world.