How do walruses sleep in the water without drowning?
Lifeguards rescue hundreds of people from drowning each year, and despite harrowing scenes from “Baywatch” indicating otherwise, most of those rescues are probably due to something mundane like swimmer fatigue. If people swam a bit more like walruses, lifeguards might be out of a job. Although clumsy on land, these aquatic mammals become pictures of grace underwater. Their four flippers propel them to speeds of up to 22 mph (35 kph), and their well-tuned circulatory systems enable them to spend more than 10 minutes underwater before coming up for air. Their hardy bodies — male Pacific walruses may weigh as much as 3,748 pounds (1,700 kilograms) — can even tolerate frigid arctic waters as low as -31 degrees Fahrenheit (-35 degrees Celsius) [source: SeaWor
