Along with the brown bear, the polar bear is one of the largest of the bear species. The white fur that covers polar bears’ bodies means that they are sometimes referred to as “white bears.” Polar bears are strong swimmers, and it is said that they can swim for distances of up to 65km, at a speed of 6.5km/h. They also have acute senses of smell and hearing, useful when hunting as this allows them to detect the scent of seals swimming beneath the ice. Polar bears are able to endure a lean diet or periods of fasting, and can survive up to six months on only one seal. Except for during mating season or when females are bringing up young, polar bears are solitary animals. Male bears and female bears who are not pregnant do not hibernate.