Large and In Charge: The Southern Elephant Seals of Antarctica
Named for the males’ exceptionally large and inflatable noses, the southern elephant seal currently holds the title for the largest member of the carnivore family, and the largest seal on the planet. They can most commonly be spotted during your Antarctica cruise lying in large groups along the coastline, bathing in the intense sunlight, nursing young pups, or playfully swimming around in the waters offshore. If you don’t see them first, you’ll most definitely smell these spectacular creatures!
How Are They Different from Northern Elephant Seals?
At first glance, the northern and southern elephant seals are remarkably similar in appearance. They’re both very large, noisy, smelly, and the males of both species share a distinctive elephant-like nose. However, there are two main differences between the seals, the first and most important being about 10,000 miles of ocean separates them. The northern elephant seal ranges from the southern tip of Baja, Mexico to the Aleutian Islands of Alaska in North America. On the opposite end of the globe, the southern elephant seal’s range is restricted to the cooler waters of the Southern Ocean.
Secondly, southern elephant seals outweigh their northern counterparts by about 1,700 kilograms. Male southern elephant seals can reach upwards of 4,000 kilograms (8,800 pounds), six meters (20 feet) in length, and on average, have a much larger nose than the northern elephant seals.
Currently, it is unclear how two species that look very much alike ended up on opposite ends of the planet. Scientists predict that at some point in their history, they were once just one species. Over time, environmental factors including ocean temperature, food availability, predation, and geography may have caused the single elephant seal species to diverge, or split, and evolve into the two distinct species that they are today.
Diving Deep for A Meal
Southern elephant seals have been recorded to dive up to 2,133 meters (7,000 feet) and can stay under water for nearly two hours! Their large, bulging eyes allow them to seek out prey in areas with low light levels. When it gets too dark, their long, sensitive vibrissae, or whiskers, allow the seals to probe around the water for prey. Using their tiny, sharp teeth, the seals can dig through the mud or simply snatch prey items out of the water. Their diet is thought to be largely composed of squid, mollusks, krill, cephalopods, and algae. There may be much more to their diets, but their long and deep diving trips can make it difficult for scientists to accurately track them and determine what they eat.
Breeding Season: A Tale of Beachmasters and Weaner Pods
The breeding season, which lasts from August to November, is the best time to see southern elephant seals hauled out on land. During this time, the larger males will fight one another to establish dominance over a particular section of beach. The dominance fights can last for hours, and can end in serious injuries to one or both males. Luckily, their thick skin protects them, and keeps them in the game. Vocalizations are also very common during these fights, and are amplified by inflating their trunk-like noses with air. Once a ‘beachmaster’ has been established, he will gather a “harem” or a group of 40-50 females that he will vigilantly monitor and defend until the end of the breeding season.
Females give birth to a single pup, which they will nurse for up to 23 days. After this time, the females will head back out into open water to feed and regain their energy after an energetically taxing breeding season. The pups or ‘weaners’ will be left to fend for themselves, and congregate into groups with other young seals called ‘weaner pods’ for the next four to six weeks. The weaner pods then face the dangerous task of leaving their safe beaches and descending into open ocean for the first time. Orcas, one the southern elephant seals only known predators, have been known to snatch up young elephant seals during this time. It’s a dangerous life in Antarctica, even for cute baby seals.
Working With Southern Elephant Seals
On King George Island in the Antarctic Peninsula, southern elephant seals are monitored on a weekly basis from October to March using non-invasive methods. Every week, scientists at the Copacabana field station walk along the island’s many beaches and record how many seals they see. Adults, sub-adults or young adults, and pups are included in the survey, along with their behaviors. For most of their time on land, the seals are found sleeping alongside other seals in wallows, or depressions in the ground filled with mud and feces. It’s a challenging way to spend an afternoon, especially if you’ve been caught downwind of a wallow.
Occasionally, elephant seals can be seen laboriously hauling their way through an entire penguin colony, disturbing everything in their path and not seeming too phased by the chaos that ensues. However slow they may move, their size alone poses a threat to unhatched penguin eggs and even adults sitting tightly on their nests. This is bad news for scientists trying to study the penguins, but is worth documenting nonetheless. Sometimes, they’ll find the perfect napping spot right on the edge of a colony, where they are then subjected to the curiosity of young penguins. The chicks will run around the large, unaware object, and may even jump on top of it to figure out exactly what it is. In rare occasions, an elephant seal’s decision to haul out in the middle of a penguin colony has resulted in the failure of every one of the colony’s nests. It’s an unfortunate event, but there’s no getting in the way of a 4,000-kilogram seal and its nap!
If the seals wake up and see an unfamiliar object, such as a scientist, walking towards them, they’ll open up their large mouths and display their many sharp, tiny teeth. This is usually a silent display and is meant only as a warning. If they’re feeling especially threatened, or if there’s a scientist that has come too close, they’ll start vocalizing and move towards the threat in an aggressive way. At this point, it’s best for the scientist to abandon the survey and find a safe way out of the situation. They may seem slow, but they can move surprisingly quick and cause a lot of damage if they feel threatened.
Southern elephant seals were hunted nearly to the brink of extinction for their blubber during the 18th and 19th centuries. In response to the decline of southern elephant seals and other Antarctic marine mammals, wildlife conservation efforts including the Marine Mammal Protection Act and the Antarctic Treaty were passed. After the increase in protection, southern elephant seals in Antarctica have seen a significant increase in their population. Although they are considered a species of least concern, their populations have occasionally seen downward trends. Scientists predict that changing ocean temperatures that lead to a decrease in food availability may be to blame. More concrete evidence concerning their unique diets and behaviors is needed to help researchers understand how to better conserve these giants of the sea.