Running a distance is the most basic form of racing, but races may be conducted in vehicles, such as boats, cars, motorcycles, bicycles and aircraft; or with animals such as horses or dogs. Races may also be conducted with other modes of transport such as skis, sleds, skates or wheelchair; or other forms of movement such as swimming or walking. In a relay race members of a team take turns in racing parts of a circuit or performing a certain racing form.