"You see," he went on after a pause, "it's as well to be provided for everything. That's the reason the horse has anklets around his feet." "But what are they for?" Alice asked in a tone of great curiosity. "To guard against the bite of sharks," the Knight replied.
Alice's Adventures in Wonderland & Through the Looking-Glass - Chapter 8 (p. 105), The Macmillan Company. 1966