The southern elephant seal is a true seal and is the largest pinniped (seal or sea lion) and carnivoran (hairy carnivore) in the world. Adult males are enormous – at least six times larger than polar bears and nearly twice the size of the next largest seal (the northern elephant seal). Males reach lengths of nearly 20 feet (6 m) and weights of more than 8000 pounds (3700 kg). Females are much, much smaller, and the males’ large size is the result of their territoriality and their habit of developing harems of several females with which they have sole mating rights.
The southern elephant seal is one of two living species of elephant seals. These two species get their name from the trunk-like nose that males develop as they become sexually mature. Only the strongest, most dominant males win the right to mate with females, and ninety percent of males die before developing a harem. Harems defended by the most powerful males may reach sizes of 120-150 females. Fights between dominant males and challengers can be long, bloody, and extremely violent, with the loser often suffering serious injury. Both pupping and mating take place simultaneously on ice-free beaches. Since females continue to nurse their pups throughout the mating season, pups are often in danger of being trampled by brawling males. Even though the pups are often the offspring of one of the fighting males, apparently the risk of losing part or all of a harem is enough to potentially kill some pups while defending it.
Southern elephant seals are open ocean predators and spend much of their time at sea. They only come to shore to reproduce and to molt their fur. The rest of the year is spent feeding at sea, where they rest by floating at the surface and feed by diving to significant depths in search of large fishes and squids. Their time at sea often brings them far from their breeding areas, and they may cover very long distances between times spent on land. Large southern elephant seals have few predators, but killer whales, leopard seals, and some large sharks are known to feed on this species.
Historically, southern elephant seals were hunted to very low numbers because of the value and volume of their blubber, which was rendered into oil. Commercial hunting ceased in 1964 because numbers were too low to be worth the long trip to the Southern Ocean. Since that time, populations have rebounded nicely, and the southern elephant seal is considered a species of least concern. However, potential impacts of expanding Southern Ocean fisheries and ongoing climate change on the populations of this seal are not well known, so it is important to continue to study and monitor this and other Antarctic seals.
Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.