section_path: Anatomy/Fur/Thermoregulation
section_name: Thermoregulation
paragraph_text: Thermoregulation
  
  Hair length is not a factor in thermoregulation: for example, some tropical mammals such as sloths have the same length of fur length as some arctic mammals but with less insulation; and, conversely, other tropical mammals with short hair have the same insulating value as arctic mammals. The denseness of fur can increase an animal's insulation value, and arctic mammals especially have dense fur; for example, the musk ox has guard hairs measuring 30 cm (12 in) as well as a dense underfur, which forms an airtight coat, allowing them to survive in temperatures of −40 °C (−40 °F). Some desert mammals, such as camels, use dense fur to prevent solar heat from reaching their skin, allowing the animal to stay cool; a camel's fur may reach 70 °C (158 °F) in the summer, but the skin stays at 40 °C (104 °F). Aquatic mammals, conversely, trap air in their fur to conserve heat by keeping the skin dry.