Elephant Seal Family

Nursing costs a northern elephant seal mother everything she brought ashore. For roughly 26 to 28 days she eats and drinks nothing, converting her own blubber into milk that climbs to about 55 percent fat, and she leaves the beach having shed more than 40 percent of her arrival body mass. The pup, meanwhile, gains about 10 percent of its birth weight every day, ballooning from around 45 kilograms to 130 or 150. Then the milk stops, the mother returns to the open ocean, and the pup fasts on the sand for weeks while teaching itself to swim. The dark coat visible on this one is already giving way to the sleek silver-gray of weaning.