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Introduction

Adult whale 

Whales have fascinated us for centuries.

"Nor was it his unwonted magnitude, nor his remarkable hue, nor yet his deformed lower jaw, that so much invested the whale with natural terror, as that unexampled, intelligent malignity which, according to specific accounts, he had over and over again evinced in his assaults."

-- Herman Melville, MOBY DICK

This quote from Herman Melville's classic novel echoes tales told throughout recent centuries -- stories in which the great sperm whale is labeled "leviathan," "monster," and "beast." For hunters, until as recently as the the late 1980s, slaughtering these whales with harpoons was not only good business, but an act of bravery. Whaling is a treacherous business: at an average of 62 feet long, the sperm whale (Pyseteridae catadon) is the largest of all toothed whales and a fearsome adversary.

Yet beneath the surface, sperm whales possess more than intimidating girth. As you see in the NATURE program SPERM WHALES: THE REAL MOBY DICK, the efforts of Jonathan Gordon and other researchers to study the whales' physicality, modes of communication, and social interactions contribute to our understanding of the underwater world.

A giant among marine mammals, a male sperm whale weighs between 40 and 60 tons. Smaller females reach a maximum weight of only 18 tons and measure about 35 feet. Both sexes are born with thick gray skin that darkens in color with age. As a whale matures, this thick covering may bear the scars caused by hunters' weapons, fights over dominance, or wounds picked up while defending young. One of the whales Dr. Gordon tracks on NATURE, an enormous adult male named Big Hal, carries on his forehead numerous scars of previous battles with rival bulls over females.

The sheer size of a sperm whale is overwhelming. Its submarine-shaped bulk is capped with a huge, blunt-edged head, a full third of its body.

Two whales 

Whales communicate with each other by clicking.

This head is actually a sophisticated communications center. Scientists believe that whales' heads contain organs that broadcast and receive the loud clicks, called "clangs," that form their language. This clicking noise is sent and received much like sonar on a submarine. A whale's head is so large that what sounds to researchers like several clicks can actually be just one. As Jonathan Gordon explains, "It's the sound of the clicks bouncing around inside its head."

Sperm whales "echo-locate" by bouncing a click sound off an object, such as a squid, and timing how long it takes for the echo to travel back to them. The whale can then judge the distance to its next meal in the darkest of waters. Male adults also use loud clicks to announce their presence with authority, while mothers and their young click to stay in communication. Thus connected, a cow can leave her offspring alone while she dives for food.

These sounds are important to sperm whales' daily lives -- and to the researchers who attempt to locate and track them. Using an underwater microphone called a hydrophone, Dr. Gordon and his colleagues can pinpoint a whale's exact location. A whale's head contains the biggest of all animal brains.While the animals follow surprisingly straight courses, they can cruise at the same speed for hours on end, often at night, when visual tracking is useless.Sperm whales can undertake these long trips in part because of their tail fluke, the longest sported by any whale. Located aft and positioned much like the propeller of a submarine, this powerful tool can thrust a whale through the sea at a rate of 20 knots, or 23 miles per hour. This flailing tail is so massive that whale hunters terrified of its destructive power called it "the hand of God." To hunt for the tons of squid and fish it must consume, a male sperm whale will descend to depths exceeding 3,000 feet. A rich supply of fish lies in the deep waters, where the continental shelf drops off and the ocean floor plummets down thousands of feet. All marine mammals rely on air to breathe, so, to make a deep dive, a whale holds its breath for as long as 90 minutes. Sperm whales breathe through blowholes located on top of their heads. As the diving whale descends, its heartbeat slows and its body naturally conserves the oxygen in its bloodstream, channeling it to vital organs like the the heart and brain.

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