More Fun At the Expense Of My Life

I thought it was pretty bad that I was bleeding to death. Then sharks showed up around our brig. The good news is the lawyer, Mutherford, thought of a swell shark trivia question to pass the time until the brig sinks and the sharks eat us. As usual, none of the crew or me knew the answer.

If you can get it right, if you can say why Mutherford isn't worried about being eaten by sharks, and if Flarq lives long enough, you got yourself a scrimshaw, mate:

A bunch of sailors who liked math went swimming in shark-infested water. Each of them luckily had a knife and incredible shark-killing skills. After ten minutes, all the sharks were dead. None of the sailors got killed. The sailors hauled the dead shark bodies onto their deck. One of the sailors noted that during the scrap, there was four times as many sailors in the water as sharks. Another sailor said that the number of legs they now had was the same as the square of the number of sharks. A third said that the number of sailor legs was 14 more than the total number of sailor and shark heads. How many sharks had got killed?