LAST week I was watching a herring gull chick emerging from its egg. On the top of the bill of each young bird is a structure known as an egg tooth.

This works like a sharp chisel and the young birds bash the inside of the egg until the shell breaks. Once the young gull has escaped and dries out, the egg tooth drops off because it is obviously not needed any more.

There is nothing more pathetic-looking than a young bird which is still wet after hatching. Some song birds are hatched naked and look like little reptiles.

Gulls, however, have more feathers on them and soon learn to walk about and demand food from their parents. But they wouldn't escape from the egg if it was not for the egg tooth!