Surface waterbodies fed by (often warm) groundwaters rising to the surface are scattered in dry landscapes of Africa, the Middle East, Eurasia, North America and Australia, but also occur in humid landscapes. Algae, floating plants and leaf fall support waterbugs, crustaceans and small fish making simple foodwebs with some locally restricted species found nowhere else. These ecosystems are sometimes important waterholes for birds and mammals, in otherwise dry landscapes.