The remarkable thresher shark sports a tail that's as long as the rest of its body, and it puts this extraordinary appendage to good use. When the solitary shark is hunting, it first uses its tail to herd prey by violently slapping the water's surface. Researchers believe that the shark also uses its tail when it goes in for the kill, whacking its prey to stun it into submission.
In Fishes of the Open Ocean, Pepperell writes that historic accounts tell of thresher sharks attacking whales, and notes that while these stories seem highly unlikely, they do make for fascinating reading. One eyewitness claimed that the thresher's tail was "like the lashing of a gigantic whip, while the blows are audible for two miles on a calm day. So heavy are they that strips of blubber are cut by them from the back of the hapless whale."