Read War of the Whales for Free Online Page B

waters are the most transparent in the world, with visibility of more than 200 feet. The 30 low-lying islands and hundreds of smaller cays of the Bahamas were once underwater coral reefs that became dry land when the sea level dropped following the last ice age, 20,000 years ago. Ringed by pink and white sand beaches, the islands barely peek above sea level. From the air, you could see where the pale turquoise of the shallows shifted quickly to the royal blue depths of Great Bahama Canyon.
    Canyons on land are created by the steady erosive force of rivers. Underwater, it’s the ceaseless gyre of the ocean currents that carve their signature into the seabed. The Bahamas were once joined in a contiguous landmass with Florida and Cuba. Over the course of 150 million years, the Atlantic and Gulf Streams ground away at the limestone ocean floor, creating a 3-mile-deep, 140-mile-long underwater canyon separating the Bahamas from the mainland. The Great Bahama Canyon is the largest, deepest gorge in the world, on land or at sea—twice as wide and three times as deep as Arizona’s Grand Canyon.
    Beaked whales have lived in Great Bahama Canyon for 40 million years, ever since they migrated from the shark-infested reefs guarding the Atlantic side of the islands. In the canyon, they found a feeding ground rich with hard-shelled nautiloids that fed on microorganisms near the surface. Before they learned to hunt with sound, beaked whales foraged visually, alongside other whales and fish. To escape predators, their hard-shelled prey descended to the dark depths during sunlight hours, returning to the upper layers at night to feed in the relative safety of darkness.
    The upper 600 feet of the ocean is called the sunlight zone, where plants dependent on photosynthesis and the marine life that feed on them live. Below 600 feet lies the twilight zone where almost no light penetrates, even in the transparent waters of the Bahamas. To follow their prey into the twilight zone, and even deeper into the lightless midnight zone below 2,500 feet, beaked whales had to learn to hunt in total darkness—which required echolocating with sound.
    Not all whales echolocate. Echolocation, or “biosonar,” was an adaptation that emerged relatively early in cetacean evolution. The fossil record of whales reveals a radical metamorphosis from furry, hoofed land-dweller to sleek marine mammal. Forelegs gave way to fins, hind legs and hair disappeared, tails transformed into flukes, and nostrils receded high onto the head to become blowholes suitable for breathing air at the ocean’s surface. The oceans offered whales a buoyant and spacious home with few predators and abundant food.
    Some whales became filter feeders, trapping tiny krill in the baleen brushes of their mouths. Released from the weight constraints of terrestrial gravity, these “baleen” whales evolved into the largest animals ever to roam the world. A 100-foot-long, 150-ton blue whale could consume up to 8,000 pounds of krill in a day.
    Other whales, hunting in packs, used their teeth to seize their prey. These “toothed” whales—including dolphins, * orcas, beaked whales, sperm whales, and others—developed the ability to hunt and navigate in the dark using sound, the same way that bats do. Though bats and toothed whales have evolved different specialized anatomy for the task, the principle is the same: they emit high-frequency sound pulses and listen for the echo. The distance between their two ears—which act as separate receivers—allows echolocators to triangulate the precise distance, direction, and dimensions of an object. 1 Other animals navigate with biosonar. Shrews have been shown to echolocate underground, and blind humans can learn to echolocate by tapping a cane—or simply by making clicking sounds with their mouths—and then listening for the echo from nearby objects.
    During their first 10 million years in the Great Bahama Canyon, beaked whales developed primitive