It took Herman Melville 135 chapters to get to the part in his 1851 classic Moby Dick when the massive sperm whale and the peg-legged Captain Ahab finally do battle. No spoiler here: Moby Dick wins, smashing his enormous head into Ahab's ship, the Pequod, and sinking it.
But it took 165 years for an international team of scientists to finally probe this burning question: Would a sperm whale actually use its massive noggin as a battering ram to down a whaling ship five times the animal's size?
The short answer: It probably could - and live to tell the tale.
This question, it turns out, is "highly controversial," and "has been hotly debated" since at least 1851, according to the recent study in PeerJ. A sperm whale's huge forehead, you see, is a very bizarre thing - "one of the strangest structures in the animal kingdom," in the words of the study's lead author, Olga Panagiotopoulou, who is an evolutionary morphologist at Australia's University of Queensland and expert on the anatomy, bone biology and mechanics of large animals.
And the forehead's purpose has long been the subject of speculation.
Male sperm whales can be 60 feet long, and their foreheads make up one-third of their length and a quarter of their body mass. Inside are two oil-filled sacs, one atop the other. The spermaceti organ is on top - it holds not sperm, but the prized lubricating oil that sent Captain Ahab-types on the hunt for the mysterious deep-sea dwellers. On the bottom is the junk sac, or, as the study refers to it, "the junk."
Previous research has established that the sacs help with the whale's echolocation, and other studies have suggested that they provide buoyancy or help the whales use sonar to debilitate prey, the study says. No one, however, had ever before studied whether sperm whales can actually use their foreheads as battering rams.
That idea was popularised by Moby Dick, which was inspired in part by the real-life stories of a sperm whales accused of downing 19th-century whaling ships, including the Nantucket ship Essex in 1820. That ship's first mate, Owen Chase, wrote a book that "described the whale's head as admirably designed for this mode of attack," Panagiotopoulou said in a statement.
Panagiotopoulou also said males' heads are much larger than females, which could also be a clue that points toward a ramming function. That size difference often occurs in species in which males compete for females, such as bottle-nosed dolphins, killer whales and goats (which, amazingly, whales are somewhat related to).
So it could be that male sperm whales engage in head-ramming duels when fighting for ladies. The stakes, after all, are high: One male sperm whale can have a "harem" of up to 40 females, according to the NOAA's National Marine Mammal Laboratory.
But ramming is a controversial notion, the study notes, because the anatomy inside the forehead is so important that it might be injurious or even fatal. Would the sperm whale have evolved to do something so stupid?
To find out, the researchers - from Australia, the United States, England and Japan - did simulated sperm whale crash tests to determine whether the junk, which houses several connective tissue partitions, could actually act as a shock absorber that protects the whale when it smashes its head into something. They tested three models: One junk with 12 partitions, one with six, and one with none. In the accompanying image, the junk is outlined in blue and its partitions are the vertical blue lines; the spermaceti organ is the empty yellow part above.
Their conclusion: Ramming with the spermaceti organ could be damaging to the whale and its sonar system. But if a whale were to ram with the junk, the connective tissues act as a "protective mechanism" that can help blunt blows. That idea that they bash with the junk is supported by observations that sperm whale foreheads usually have scars on the exterior of the junk, the study said.
"This mechanism is important to reduce impact stress and protect the skull from failure," Panagiotopoulou said.
The study didn't determine whether sperm whales actually ram to fight each other - or down ships. But, it decided, they could very well do so and survive.
"Although the unique structure of the junk certainly serves multiple functions, our results are consistent with the hypothesis that the structure also evolved to function as a massive battering ram during male-male competition," the study said.
So there you have it, aspiring Captain Ahabs. The Moby Dicks out there are well-prepared to take you on.