杏吧原创

鈥淕OD hunt us all if we do not hunt Moby Dick to his death!鈥� But it was Captain Ahab who came off worst in the encounter. And that鈥檚 not surprising. Studies of sperm whales鈥� heads suggest they鈥檙e perfectly evolved for ramming boats.

Whales鈥� foreheads contain two sacs filled with oil. In male sperm whales, these sacs are especially massive. Quite what their purpose is isn鈥檛 clear. Some biologists think they play a role in sound production or controlling buoyancy, but another theory is that the sperm whale鈥檚 massive oil-filled sac cushions the animal鈥檚 head during fights. While there are a handful of anecdotal accounts of such contests between males, evidence has been scarce.

Now Stephen Deban and his team at the University of Utah have modelled how the fluid-filled sacs would behave in a collision. They found the organ acts like a damper, cushioning the impact. It鈥檚 a bit like a syringe, says Deban, you don鈥檛 need much force to push the water out slowly, but you need to squeeze much harder to push it out faster.

That means an attacking whale could smash into an opponent鈥檚 side鈥攐r a ship鈥攁nd come out of the encounter unscathed. What鈥檚 more, whale species in which the males engage in more intense competition for mates also tend to have larger oil-filled sacs.

Whalers in the 19th century were all too aware of the dangers. The sinking of the Ann Alexander in 1851鈥攖he year Herman Melville鈥檚 Moby Dick was published鈥攊s one example. Two head-on charges from a harpooned whale were enough to send the crew to a watery grave. But the sperm whale鈥檚 weapon was also its downfall. It was the oil that made the creatures so highly prized in Melville鈥檚 time.