Catherine Heyman, age 10, of Kingston, Ont., Can., for her question:

DOES A PORCUPINE EVER LOSE ALL HIS QUILLS?

Now and then the prickly porcupine jabs a few of his quills into an enemy and leaves them behind. But he never loses all of them. In fact, a baby porcupine is born with his fair share of quills, though they are quite soft for the first 10 days or so. When fully grown he has about 30,000 spiky quills. When one is lost, a new one grows in to replace it.