That's because none of this actually happens. Turns out, the "swords," or bills, of billfish like marlin, sailfish, and swordfish, are indeed used for hunting, but not as devices to impale prey.

Their bills are like swords jutting out of their faces and like real swords, their bills are not all the same. Hey, check out this classic old sword. It's called a rapier.

It doesn’t look like much at first—barely the size of a lowercase letter on a keyboard. But that sliver floating in open water is the start of a swordfish. Although it can fit on your fingernail at ...