Arctocephalinae

Arctocephalinae is a subfamily of the Otariidae, the family that includes fur seals and sea lions. It comprises two extant genera, Arctocephalus and Callorhinus, commonly referred to as fur seals. Members of this subfamily are marine mammals adapted to life in temperate to subtropical oceans of the Southern Hemisphere and parts of the North Pacific, where they form large breeding colonies on islands, coastal rocks, and shelves.

Anatomy and biology: Fur seals are eared seals with a robust, streamlined body and a dense fur coat that helps insulate them in cold water. They have rotating hind limbs that can be folded under the body for efficient movement on land, enabling relatively agile locomotion at breeding rookeries. Sexual dimorphism is pronounced, with large males establishing territories during the breeding season, while females care for and nurse their young.

Behaviour and reproduction: Fur seals typically form seasonal colonies. Males defend breeding harems and vocalize or display to deter rivals, whereas females give birth to pups after a gestation that often results in asynchronous timing of births across colonies. Lactation periods vary by species, and pups are weaned before dispersing to forage. Foraging ranges and diving behavior reflect prey availability and can encompass substantial depths and distances.

Diet and ecology: Their diet mainly consists of fish, squid, and other cephalopods. Foraging can occur across wide areas, with regional differences in prey selection and seasonality. They are long-lived and have historically faced hunting pressure, which reduced some populations in the past but many have recovered with conservation measures.

Taxonomy and species highlights: The genus Arctocephalus includes species such as the Cape fur seal and the Antarctic fur seal, while Callorhinus includes the northern fur seal (Callorhinus ursinus). Conservation status varies by species and region, reflecting diverse ecological pressures.