The Sperm Whale’s Deadly Call

Scientists have discovered that the massive mammal uses elaborate buzzes, clicks and squeaks that spell doom for the animal’s prey

Whalers pursued sperm whales for the rich oil in their oversized heads. Now biologists are on the tail of these deep-diving, long-lived, sociable and mysterious sea creatures. (Gerard Soury / Oxford Scientific / Getty Images)
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In 1839, in the first scientific treatise on the sperm whale, Thomas Beale, a surgeon aboard a whaler, wrote that it was “one of the most noiseless of marine animals.” While they do not sing elaborate songs, like humpbacks or belugas, in fact they are not silent. Whalers in the 1800s spoke of hearing loud knocking, almost like hammering on a ship’s hull, whenever sperm whales were present. They called the animals “the carpenter fish.” Only in 1957 did two scientists from the Woods Hole Oceanographic Institution confirm the sailors’ observations. Aboard a research vessel, the Atlantis, they approached five sperm whales, shut off the ship’s motors and listened with an underwater receiver. At first, they assumed the “muffled, smashing noise” they heard came from somewhere on the ship. Then they determined the sounds were coming from the whales.

Biologists now believe that the sperm whale’s massive head functions like a powerful telegraph machine, emitting pulses of sound in distinct patterns. At the front of the head are the spermaceti organ, a cavity that contains the bulk of the whale’s spermaceti, and a mass of oil-saturated fatty tissue called the junk. Two long nasal passages branch away from the bony nares of the skull, twining around the spermaceti organ and the junk. The left nasal passage runs directly to the blowhole at the top of the whale’s head. But the other twists and turns, flattens and broadens, forming a number of air-filled sacs capable of reflecting sound. Near the front of the head sit a pair of clappers called “monkey lips.”

Sound generation is a complex process. To make its clicking sounds, a whale forces air through the right nasal passage to the monkey lips, which clap shut. The resulting click! bounces off one air-filled sac and travels back through the spermaceti organ to another sac nestled against the skull. From there, the click is sent forward, through the junk, and amplified out into the watery world. Sperm whales may be able to manipulate the shape of both the spermaceti organ and the junk, possibly allowing them to aim their clicks. The substance that made them so valuable to whalers is now understood to play an important role in communication.

Whitehead has identified four patterns of clicks. The most common are used for long-range sonar. So-called “creaks” sound like a squeaky door and are used at close range when prey capture is imminent. “Slow clicks” are made only by large males, but no one knows precisely what they signify. (“Probably something to do with mating,” Whitehead guesses.) Finally, “codas” are distinct patterns of clicks most often heard when whales are socializing.

Codas are of particular interest. Whitehead has found that different groups of sperm whales, called vocal clans, consistently use different sets; the repertoire of codas the clan uses is its dialect. Vocal clans can be huge—thousands of individuals spread out over thousands of miles of ocean. Clan members are not necessarily related. Rather, many smaller, durable matrilineal units make up clans, and different clans have their own specific ways of behaving.

A recent study in Animal Behaviour took the specialization of codas a step further. Not only do clans use different codas, the authors argued, but the codas differ slightly among individuals. They could be, in effect, unique identifiers: names.

Whitehead, who was a co-author of the paper, cautions that a full understanding of codas is still a long way off. Even so, he believes the differences represent cultural variants among the clans. “Think of culture as information that is transmitted socially between groups,” he says. “You can make predictions about where it will arise: in complex societies, richly modulated, among individuals that form self-contained communities.” That sounds to him a lot like sperm whale society.

But most of a sperm whale’s clicking, if not most of its life, is devoted to one thing: finding food. And in the Sea of Cortez, the focus of its attention is Dosidicus gigas, the jumbo squid.

One afternoon, i’m sitting on the deck of the BIP XII reading Moby-Dick when Bill Gilly happens by. “Have you reached the squid chapter?” he asks. I tell him I have not. Gilly waves his hands in mock dismissal—“Gaaah!”—and continues on his way. Apparently, I am not worth talking to until I have read it. I flip ahead to “Squid,” which is only two pages long. My edition of Moby-Dick has 457 pages, but for Gilly, the rest of the book might as well not exist.

Gilly, a biologist at Stanford University, studies the jumbo squid. “For animals that live two years at most,” he says, “they sure do live it up.” In that time, the squid grow from larvae that could generously be called cute into far more menacing specimens that can be more than six feet long and weigh more than 80 pounds. They can swim more than 100 miles a week and recently have expanded their range. Native to subtropical waters, they were caught in 2004 by fishermen as far north as Alaska. There may be a couple of reasons for this. One is that climate change has altered the oxygen levels in parts of the ocean. Also, many top predators, like tuna, have been heavily fished, and squid may be replacing them, preying on fish, crustaceans and other squid. No one knows the consequences of this great sea-grab, which extends not just to Alaska, but apparently to other corners of the ocean. In the Sea of Cortez, squid “certainly weren’t a prominent presence earlier in the century,” Gilly says. “Steinbeck mentions them two, maybe three times in Sea of Cortez.” (Gilly’s wife is a Steinbeck scholar at San Jose State University.)


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