Woodpeckers' heads are filled with pockets of air that cushion their head bones as they drill for food or bore the tunnels that lead to their nests. Tusks are simply large teeth that protrude outside an animal's mouth.
Baby birds have an egg tooth, which they use to peck out of the egg.
Once hatched, the chick loses the tooth. No, birds have many songs. No, each zebra has its own stripe pattern, just as each person has his or her own fingerprint. Moose, caribou, and deer are some animals with antlers. A horn is hollow, made up of a hard skin tissue similar to a fingernail.