Except for the semi-molten asthenosphere, the mantle is solid. Biosphere Earth scientists also speak of a biosphere, the zone in which the planet s life forms survive. The most visible of these life forms are either plants stationary creatures that harness energy directly from the sun and lithosphere and animals, life forms that can generally move about and survive by eating plants or other animals. Plants carpet most of Earth s surface, giving it its greenish color. Small plants also float near the surface of Earth s oceans and lakes, within range of sunlight.
Animals live everywhere plants live, also surviving at much greater depths in Earth s waters.
In addition, some animals can fly in the lower reaches of the atmosphere, and some burrow in the upper reaches of the lithosphere. Over much of Earth s land surfaces, the outermost crust is covered by an extremely thin film where tiny plants and animals mix with inorganic materials to form a wondrous thing called soil. The great majority of Earth s land plants grow in soil. Humans use vast areas of Earth s surface to cultivate their favorite food plants. From a perch in the atmosphere, these areas often appear as rectangular shapes in various shades of green.