Aquatic biomes include both freshwater and marine biomes. Freshwater biomes are bodies of water surrounded by land—such as ponds, rivers, and lakes—that have a salt content of less than one percent. Marine biomes cover close to three-quarters of Earth’s surface, including the ocean, coral reefs, and estuaries.

Deserts are dry areas where rainfall is less than 50 centimeters (20 inches) per year. They cover around 20 percent of Earth’s surface. Deserts can be either cold or hot, although most of them are found in subtropical areas. Desert wildlife consists primarily of reptiles and small mammals.

Forests are dominated by trees, and cover about one-third of the Earth. It contain much of the world’s terrestrial biodiversity, including insects, birds, and mammals.

Savannas are found closer to the equator and can have a few scattered trees. They cover almost half of the continent of Africa, Australia, India, and South America.

A tundra has extremely inhospitable conditions, with the lowest measured temperatures, a low amount of precipitation, poor nutrition soil, and short summers. It always located near polar circles.

both hot and moist in summer, but different in winter