The sperm whale has the largest brain on Earth, more than five times heavier than a human’s, and a head that fills a third of a body up to 52 feet long, with its blowhole pushed to the front left so its spray angles sideways. It routinely dives about 2,250 meters, over 7,300 feet, for more than an hour. Flexible cartilage lets its ribcage and lungs collapse under the pressure, yet older whales’ skeletons show avascular necrosis, bone death like that from decompression sickness, while calves’ bones are smooth. The head holds the spermaceti organ, a waxy fluid that whalers mistook for semen. Air forced through the monkey lips makes clicks that bounce through the wax and out as focused sonar reaching 236 decibels, the loudest animal sound known.

Tag studies on whales and squid showed the clicks lose too much pressure to stun prey, so they serve range and resolution. A male eats about 3% of its weight a day in squid, sucked in whole, since whales with deformed jaws or no teeth stay healthy; the lower teeth, up to 26 per side at a kilogram each, are for fights between males. Females and calves live in tropical matriarchal units of six to nine, sometimes 20, while males roam toward the poles. Against orcas the adults form the marguerite, heads in and tails out around the calves. Families speak in rhythmic click patterns called codas, and clans of thousands share one dialect and do not mix with other clans in the same waters. In 1820 a sperm whale rammed and sank the Nantucket whaleship Essex, inspiring Moby Dick.

• Saucer sized sucker scars on their skin and undigested beaks in their stomachs show their fights with giant and colossal squid.
• Iron rich feces released at the surface fertilize phytoplankton blooms that pull carbon down, a cycle called the whale pump.
• Spermaceti oil lit city street lamps and lighthouses and lubricated early industrial machinery.
• Ambergris forms around irritating squid beaks in the gut and was prized as a perfume fixative.
• Whaling cut an estimated 1.1 million sperm whales to about 360,000, leaving an estimated extra two million tons of carbon in the air each year.