"What keeps an oyster closed?"
"The muscle, sir, because when it is dead it flies open."
"Very good. Do muscles grow tired?"
"Mine do," said Colin, smiling, "and I suppose the muscles of oysters are the same way."
"Exactly. Now what happens is this. The starfish crawls along until he finds an oyster which he thinks will suit his taste. As he crawls near or on it, the oyster closes up tight. The starfish—taking plenty of time—fastens himself to the shell, having two of his 'arms' on one shell and the suckers of the other three 'arms' attached
to the other shell. Then the starfish starts to pull."
"But isn't the oyster stronger?"
"Much stronger," agreed the director, "but the starfish doesn't know enough to quit. The pull he exerts is not so powerful but it is relentless and unceasing and no oyster muscle can resist it for more than a few hours. Presently the shell gapes open. The starfish lumbers over and commences to feed, other starfish often coming to enjoy the feast."
"And are there starfish enough to injure the beds?"
"Myriads of them. A starfish is not easy to kill, moreover, because if any of the arms are cut off he will grow a new one."