The polar bear (Ursus maritimus) is a bear native largely within the Arctic circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak bear, which is approximately the same size.[3] An adult male weighs around 350–680 kg (770–1,500 lb),[4] while an adult female is about half that size. Although it is closely related to the brown bear, it has evolved to occupy a narrow ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet.[5] Although most polar bears are born on land, they spend most of their time at sea (hence their scientific name meaning "maritime bear") and can hunt consistently only from sea ice, so spend much of the year on the frozen sea.