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Today on Animal Fact Files we’re discussing elephant seals. There are two living species of elephant seals: the northern elephant seal and the southern elephant seal. These are true seals: they don't have external ears and they can't tuck their tail under their body to help them walk. They're also some of the largest living seals alive today. They're bigger than a walrus and even some whales! Male elephant seals top the charts weighing anywhere between 4,400 to 6,600 pounds (2000-3000 kg) at their largest and measuring 15 feet (4.5 m) or longer in some extreme cases. Females are significantly smaller, displaying one of the most iconic cases of mammalian sexual dimorphism. On average, female elephant seals are four times smaller than males weighing in at 1,500 to 2,000 pounds (700-900 kg) at their fullest and reaching up to 10 feet (3 m) in length. Southern elephant seals are slightly larger than northern elephant seals at full size, however, they don't start out that way.

Elephant seals spend a majority of their time at sea, somewhere around 80% of their lives. And during that time, upwards of 90% is spent below the waves. Yes, these animals are mammals and require air to breathe, however, their trips to the surface are brief. Underwater, elephant seals seek out prey such as fish and squid, occasionally taking crustaceans from the ocean's bottom. Males are more likely to hunt over continental shelves where they search the ocean floor for food. Female elephant seals forage further out to sea in open water. Although these mammals are gregarious on land, they're believed to live more solitary lives at sea. The short time they spend on shore is reserved for breeding and molting.

Elephant seals haul up on shore during the winter. For northern elephant seals, which live in the northern hemisphere along the Pacific coasts of North and Central America, this typically begins around December. Southern elephant seals live throughout the Atlantic, Pacific, and Indian Oceans in cold parts of the southern hemisphere and start their haul out around August. Males arrive first and females flock in shortly after. Within a week of their arrival, the females give birth and spend the next three to four weeks nursing their pup. The babies grow rapidly during this period, however, northern elephant seal mothers feed their pups a few days more than southern elephant seal moms, so the northern elephant seal babies are slightly larger than southern elephant seal babies when their mother leaves them. 

Baby elephant seals have dark fur that helps them keep warm but isn't useful for swimming. When their mother's leave a mere month after their birth, the pups remain on shore to molt their baby fur and grow in new fur that's more adapted to water. They teach themselves to swim and hunt, remaining in shallow areas before venturing further into the ocean. It takes about 8 years for the juveniles to reach maturity, although some females start breeding as early as their 3rd year.

Prior to leaving their newborn pup behind, female elephant seals mate with the male in charge and then leave the beach. They don't eat during their entire month here. Males go even longer without eating, spending upwards of three months defending a group of females with which to breed. Male elephant seals fight over harems. They have long, sharp canines for slashing at each other's necks and chest. Their long, fleshy nose – called a proboscis – is used to make roaring calls and display their sexual prowess. Most fights don't end in death, but nearly all male elephant seals have scars to show for them. The main male in charge is called the "beach master" and he'll have subordinate males which help him defend his harem of upwards of 100 females depending on the size of the beach.

Giant males give no regard for pups as they trudge about the colony and fight each other. It's not uncommon for a baby elephant seal to be trampled during these matches. Even female elephant seals will bite at babies that aren't their own, sometimes fatally injuring the infants in the process. And they're not safe when they leave the beach, either. Leopard seals and some sea lions predate small elephant seal babies and all life stages are taken by great whites and killer whales. Plus, these pinnipeds have to contend with human-related threats such as the climate crisis.

At the turn of the 18th century, northern elephant seals were declared extinct multiple times. These giant animals were slaughtered en masse as they hauled up on beaches. Some estimates believe fewer than 100 individuals survived before protections were put in place, and it's from these few dozen that the entire northern elephant seal population has bloomed. Of course, like cheetahs, this population bottleneck puts their entire population at risk because they have little genetic diversity meaning the whole group is susceptible to disease. Southern elephant seals were also hunted, although their more remote nature helped keep their populations stable. Today, there are at least three genetically distinct southern elephant seal populations.

Elephant seals may live one to two decades in the wild. They're some of the deepest diving seals alive, sometimes even out diving whales. In a single dive, an elephant seal can go more than 5,000 feet (1,500 m) below the surface. This is an extreme, but they regularly dive between 1,300 and 2,600 feet (400-800 m) deep and can hold their breath for more than an hour. The only other time elephant seals leave the water is when they molt. Each year, these vertebrates slough off their old fur and grow new fur to take its place. Entire chunks of their skin fall off with the fur, so they look a little scrunkly during this process.

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