It includes all the Aquatic Ecosystems on the earth’s surface. Aquatic biomes are grouped into two, Freshwater Biomes (lakes and ponds, rivers and streams, wetlands) and Marine Biomes (oceans, coral reefs, and estuaries). These biomes make up about 73% of the earth’s surface.

Life forms in these waters depend on abiotic factors such as sunlight entering the waters, temperature, pressure, salt content, and so on. Water biomes with lots of light tend to have more flora (plant) diversity, and the growth of algae and plankton is more. Small water bodies that freeze during the cold seasons, or dry out in the dry and hot seasons tend to have less diversity.

Examples of animals found in marine biomes include starfish, sharks tuna, and sea birds. Examples of animals in freshwater biomes include salmon, tilapia worms, water-surface insects, and crabs. Aquatic biomes are very important because apart from being home to millions of water animals, they also form the basis of the water cycle and help with atmospheric moisture, cloud formation, and precipitation. One example of a marine biome is the Great Barrier Reef (a coral reef system) of Australia.

An example of a freshwater biome is the Amazon River in Brazil.