The ferret is a domesticated mammal, with males being substantially larger than females. They typically have brown, black, white, or mixed fur and have a natural lifespan of 7 to 10 years. Ferrets are crepuscular, meaning they spend 14–18 hours a day asleep, and are most active around dawn and dusk. Unlike their polecat ancestors, which are solitary animals, most ferrets will live happily in social groups. They are territorial, like to burrow, and prefer to sleep in an enclosed area. A group of ferrets is commonly referred to as a "business."