Consider this list from Le Boeuf and Laws' seminal 1994 book on elephant seals:
Elephant seals are the largest of the 34 extant species of pinnipeds in the world, and one of the most sexually dimorphic marine mammals - adult males are several times more massive than females.
Alpha bull elephant seal mates with a cow.
Elephant seals are extremely polygynous compared to any other large vertebrate. One male might mate with up to 200 females, while most males will never mate.
Females fast the entire time while nursing their pups, and the largest breeding males fast for more than one hundred days during the breeding season. After losing up to 40 percent of their body mass while fasting, females then migrate at least 5,500 km and males at least 11,000 km into the ocean to find food.
A cow aggressively defends her pup while nursing, but her weaned pup must learn to swim and hunt on its own.
Elephant seals dive deeper and longer than any other pinniped, and they spend more time submerged during their long aquatic wanderings than most whales!
Elephant seals even sleep underwater.
No other large vertebrate has come so close to extinction and made such a rapid recovery as the northern elephant seal. And thank goodness it recovered: the South Farallon Islands and indeed the world would be a much poorer place without this most superlative of creatures.
PRBO biologists tag all weaned pups on SEFI and West End for permanent identification.