Next up in our discussion of awesome pinnipeds (seals and sea lions) are the elephant seals. Our intern, Trevor Derie, shares why these huge, and often extreme, marine mammals are the coolest:
The elephant seal is an extremophile when it comes to pinnipeds, leading the pack in physiological and functionality aspects. Consisting of two species, the Northern elephant seal (Mirounga angustirostris) and Southern elephant seal (Mirounga leonina), this seal is easily recognizable with its trunk and size, becoming a popular animal to document and observe during its short time periods on the beach. After being hunted to near extinction for meat and oil, the species have rebounded to near pre-hunting levels! Though the two species look completely identical, a few key differences do exist between them.
For starters, while the females of both elephant seals are relatively the same size (growing up to around 1,300 pounds on average), the Southern elephant seal males can grow much larger than their Northern counterparts. An extreme case of sexual dimorphism (differences in appearance/size between males and females), males are often five or even ten times larger than the females, with Northern males reaching up to 5,000 pounds and the Southern males growing even larger to 8,800 pounds, making them the the two largest seals and pinnipeds in the world!
The Northern elephant seal can be found in the Northeastern Pacific ocean, ranging from Northern Mexico to the Aleutian Island in Alaska, with most breeding colonies found in California during the winter. The Southern elephant seal can be found in Antarctic and sub-Antarctic waters, including southern New Zealand, the Falkland Islands, and other latitudinally similar locations. South Georgia Island presents the largest breeding colony by far, hosting 400,000 individuals! Elephant seals typically only come on land in late winter to breed and molt – a 5(ish) week process of shedding and replacing the body’s outer hair and skin layer. After this, the animals will spend the rest of their time out at sea, often migrating thousands of miles away from the breeding grounds to more food rich areas (such as the northerners travelling from California to Alaska). During this time, the animals exclusively spend their time in the water, feeding on all the available resources they can find and floating at the surface to sleep.
Presenting another case of being an extremophile, the elephant seal can dive to amazing depths for food, searching primarily for deepwater squid, fish, skates or even some sharks and crustaceans. Though primarily diving to 1,000-2,000 feet (already deep!), some individuals have been recorded to go even deeper, with a Southern elephant seal recorded dive to 7,800 feet! Since they dive so much deeper than other seal and sea lion species, their eyes are actually structured differently than other seals. In the eye, rods function in low light conditions to identify objects, but cannot discriminate colors – the primary function of cones. These seals actually have more rods than cones in their eyes, helping them hunt down below as more and more light disappears the deeper they dive.
Perhaps the most noticeable and obvious aspect of the elephant seal is the male’s proboscis – that is, the “trunk” of the seal (hence the name elephant seal). The proboscis, developing after around four years of age in mature males, is used for sound production primarily during the mating season. These sounds consist of loud roars or grunts to attract females and fend off challenging or lower-ranking bull males. During a breeding season, a successful male will mate with at least 30-50 females in his harem, should he successfully fend off challengers. However, maintaining the harem often results in a brutal and bloody battle between bulls, with challengers slamming and biting each other until one backs down. Females will birth one pup and feed it milk very high in fat (up to 50% milkfat!) for four weeks before leaving them to fend for themselves.
Though rare, there are a few elephant seals that call the Salish Sea home, with the exception of a few passers-by. Race Rocks, a small island south of Victoria B.C., hosts the northernmost known breeding colony of Northern Elephant seals, with a few males and females returning each year. More locally, four well known elephant seals (all in the same family) return annually here in Anacortes and Whidbey Island. A particular young female, Elsie Mae, has become a bit of nuisance to some in the area, as she has grown up around people and therefore is comfortable lounging on crowded beaches and even the road when molting. I had the opportunity to see her most days for field work during her molt, helping people stay a respectable distance away from her until she finished her molting and headed out to sea. Let’s hope she and her family members stay out of trouble on our busy beaches as they return each Spring!