the top of their heads. Canine teeth are much longer and have a greater diameter in adult males than those found on adult females, and this relationship holds to a lesser extent at all ages. Adult females, subadults, and juveniles are moderate in build. Distinguishing the sexes is difficult until about age five. The body is modest in size and the neck, chest, and shoulders are sized in proportion with the torso. Adult females and subadults have more complex and variable coloration than adult males. They are dark silver-gray to charcoal above. The flanks, chest, sides, and underside of the neck, often forming a chevron pattern in this area, are cream to tan with rusty tones. Variable cream to rust-colored areas are on the sides and top of the muzzle, chin, and as a "brush stroke" running backwards under the eye. In contrast, adult males are medium gray to black, or reddish to dark brown all over. Their manes can have variable amounts of silver-gray or yellowish tinting on the guard hairs. Pups are blackish at birth, with variable oval areas of buff on the sides, in the axillary area, and on the chin and sides of the muzzle. After three to four months, pups molt to the color of adult females and subadults. Males can be as large as 2.1 m and 270 kg. Females can be up to 1.5 m and weigh 50 kg or more. Newborns weigh 5.4–6 kg, and are 60–65 cm long. The teeth are haplodont, i.e. sharp, conical and mostly single-rooted, as is common with carnivorous marine mammals adapted to tearing fish flesh. As with most caniforms, the upper canines are prominent. The dental formula of the adult is Like other otariids, northern 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. Distribution and habitat The northern fur seal is found in the