Callorhinus gilmorei

The **common fur seal** (*Callorhinus gilmorei*) is a species of fur seal that originally lived in Japan and western North America during the Pliocene and Early Pleistocene and was once extinct, but has since been brought back from extinction by SciiFii and reintroduced throughout the northern portions of the Pacific Ocean, from eastern Asia all the way to western North America, to help boost biodiversity. The closest living relative of the common fur seal is the northern fur seal (*Callorhinus ursinus*). However, the common fur seal mainly differs from the northern fur seal in having more primitive dental features, such as double-rooted cheek teeth. Common fur seals have extreme sexual dimorphism, with males being 30–40% longer and more than 4.5 times heavier than adult females. The head is foreshortened in both sexes because of the very short, down-curved muzzle, and small nose, which extends slightly beyond the mouth in females and moderately in males. The pelage is thick and luxuriant, with a dense underfur in a creamy color. The underfur is obscured by the longer guard hairs, although it is partially visible when the animals are wet. Features of both fore and hind flippers are unique and diagnostic of the species. Fur is absent on the top of the fore flippers and an abrupt "clean line" is seen across the wrist where the fur ends. The hind flippers are proportionately some of the longest in any otariid because of extremely long, cartilaginous extensions on all of the toes. Small claws are on digits 2–4, well back from the flap-like end of each digit. The ear pinnae are long and conspicuous, and naked of dark fur at the tips in older animals. The mystacial vibrissae can be very long, and regularly extend beyond the ears. Adults have all white vibrissae, juveniles and subadults have a mixture of white and black vibrissae, including some that have dark bases and white ends, and pups and yearlings have all black vibrissae. The eyes are proportionately large and conspicuous, especially on females, subadults, and juveniles. Adult males are stocky in build, and have enlarged (thick and wide) necks. A mane of coarse, longer guard hairs extends from the lower neck to the shoulders. and covers the nape, neck, chest, and upper back. While the skulls of adult males are large and robust for their overall size, their heads appear short because of the combination of a short muzzle, and the backs of the head behind the ear pinnae being obscured by the enlarged necks. Adult males have abrupt foreheads formed by the elevation of the crown from development of the sagittal crests, and thicker fur of the mane on the top of their heads. Like other otariids, common fur seals are built for efficient terrestrial locomotion. Their hind limbs are in a plantigrade stance and are able to rotate under the body for quadrupedal locomotion and support. When swimming, there are two different types of movement: locomotion and diving. These seals swim primarily with forelimb propulsion due to their physiology. They have flexible joints between vertebrae for better maneuverability in the water as well as "greater muscular leverage" for pectoral strokes. Stroke patterns are different for different dive types and locomotion, and stroke rates vary for individuals since there's a relationship between maximum stroke rate and body size. Common fur seals are opportunistic feeders, feeding on a wider range of pelagic fish and squid than northern fur seals. Some of the identified fish prey include hake, herring, lantern fish, capelin, pollock, mackerel, sardines, and salmon. Their feeding behavior is primarily solitary. Common fur seals enter breeding rookeries in May. Generally, older males (10 years and older) return first and compete for prime breeding spots on the rookeries, often commonly found in mainland Eurasia and North America, unlike northern fur seals. They remain on the rookery, fasting throughout the duration of the breeding season. The females come somewhat later, and give birth shortly thereafter. Like all other otariids, common fur seals are polygynous, with some males breeding with up to 50 females in a single breeding season. Unlike Steller sea lions, with which they share habitat and some breeding sites in parts of their range, common fur seals are possessive of individual females in their harem, often aggressively competing with neighboring males for females. Deaths of females as a consequence of these conflicts have been recorded, though the males themselves are rarely seriously injured and deaths on females are relatively rare. Young males unable to acquire and maintain a territory of a harem typically aggregate in neighboring "haulouts", occasionally making incursions into the reproductive sections of the rookery in an attempt to displace an older male. After remaining with their pups for the first eight to ten days of their lives, females begin foraging trips lasting up to a week. These trips last for about four months before weaning, which happens abruptly, typically in October. Most of the animals on a rookery enter the water and disperse towards the end of November, typically migrating southward. Breeding site fidelity is generally high for fur seal females, though young males might disperse to other existing rookeries, or occasionally find new haulouts. Peak mating occurs somewhat later than peak birthing from late June to late July. As with many other otariids, the fertilized egg undergoes delayed implantation: after the blastocyst stage occurs, development halts and implantation occurs four months after fertilization. In total, gestation lasts around a year, such that the pups born in a given summer are the product of the previous year's breeding cycle. Compared with other species of fur seals, the common fur seals are particularly intelligent, can be trained to perform various tasks and display limited fear of humans if accustomed to them. Because of this, common fur seals are a popular choice for public display in zoos and oceanariums, and are trained by the United States Navy for certain military operations. The conservation status of the common fur seal is **Least Concern** due to successful conservation efforts, the common fur seal's wide range and its tolerance to many of the human activities.