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Pinnipednesday - Arctocephalus pusillus Edition

The weather out here is so hot and dry that even some of my succulents shriveled up and died. I had to go get some replacements today and move my plants further into shade. Let's cool off with some pinnipeds.

The Brown Fur Seal (Arctocephalus pusillus) is the seal you all know from those countless Great White Shark documentaries - the ones that show the sharks breaching the surface of the water off the coast of South Africa, hunting these very seals as they venture out to open waters for food. Brown Fur Seals go by different names, including common names for the two subspecies, like the South African fur seal, the Cape fur seal, and the Australian fur seal. They are the largest of all fur seals, stocky in build and with broad skulls. Their vibrissae (whiskers) can grow so long that they point past their ear flaps.


The largest Brown Fur Seals, A. p. pusillus, are found on the African coastlines, primarily South Africa. Males can grow up to 7.5 feet (2.3 meters) in body length and weigh up to 660 pounds (300 kg). Females are smaller, growing up to 5.9 feet (1.8 meters) and weighing 260 pounds (120 kg). Their cousins, A. p. doriferus, are on average slightly smaller, and found primarily along the Australian coastlines. Despite their different ranges, though, the two subspecies share many of the same behaviors.

Brown Fur Seals feed primarily on fish, squid and crab, in that order. They have been known to branch out to other cephalopods like octopus, and even the occasional bird, but approximately 70% of their diet consists of different kinds of fish. They can dive as deep as almost 700 feet (204 meters). As mentioned, they are preyed upon by Great White Sharks, but have developed some tactics to help them survive these predators. There is safety in numbers, so they will swim in large groups when they can, as the sharks like to go after lone individuals. When they swim along the surface, they will "porpoise," which increases their ability to keep watch under the water. If a group of them is attacked by a shark, they will scatter, going in all different directions to confuse the shark and increase the odds that they will all escape. When in close quarters with a shark, they will stick as close as they can to the shark's dorsal fin, staying out of reach of its powerful jaws until the shark tires and gives up.


During the mating season, Brown Fur Seals will haul up on rocky shores, gathering into huge rookeries ranging from 500 to 1,500 in number. Though most of their lifespan is spent at sea, they are never too far away from land, and the shores and shallow waters are ideal for new mothers and pups to spend some time together. Breeding starts in October, when the big males haul out and start establishing dominance with each other. During this time they will fast until the end of the breeding season, around December, to protect their females from being mated with by other males. However, females are free to choose which males they mate with, and can wander to another male's harem if they like him better. Pups are born after a gestation period of almost 12 months, just in time for their mothers to be ready to breed again.


Brown Fur Seals are incredibly curious, and will often approach photographers and scuba divers when they are at ease, though this is more likely to happen in the water, where they have more maneuverability and therefore more opportunity to escape. Though in the past they were hunted, they been protected in Australia since 1923, and in South Africa since 1990. However, they are still hunted in Namibia.

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