On land, this enormous marine mammal may be a lumbering mass of blubber, but once in water, it transforms into a graceful swimmer and remarkable diver. One of the most striking features of the northern elephant seal is the pronounced differences between the sexes (3). Males are not only significantly larger and heavier than females, but they also have (like their namesakes) a prominent, trunk-like proboscis, and a region of thickened, scarred skin on the neck, chest and shoulders called a 'chest shield', the result of numerous fights with other males (3).
The short, stiff hair of males is dark grey, fading to a rusty greyish-brown throughout the year (2). Females are generally darker than males, having a brown coat with a lighter area around the neck, which is actually scarring from being repeatedly bitten by the male during mating (2). Like other true seals (those belonging to the Phocidae family), the northern elephant seal has long, webbed feet, providing effective propulsion through the water, and forelimbs that are used to steer whilst swimming or drag themselves across land (4).