All water bodies on earth are aquatic biomes. Aquatic biomes are the largest of all biomes, because water covers approximately three-quarters of the planet, and they're divided into two major categories: marine and freshwater.
Marine biomes are saltwater and include oceans, estuaries and coral reefs. These biomes house countless species of animal and plant life. Most of the world's oxygen is provided by algae found in the marine region. Oceans are the largest marine biome. Ocean biomes are divided into four subcategories: intertidal, pelagic, abyssal and benthic. Coral reefs are found in shallow and warm marine waters. Estuaries are formed when freshwater flows into saltwater, resulting in a diverse aquatic ecosystem.
Freshwater biomes include lakes, river, ponds, swamps and wetlands that contain a lower concentration of salt than marine biomes. Lakes and ponds are much smaller than oceans and house only a fraction of the species that may be found in oceans. These bodies of water are divided into two subcategories of biomes: the littoral zone and the limnetic zone.
Wetlands include glades, swamps and marshes. These are generally very large bodies of water and home to a large variety of aquatic plant and animal life. Rivers and streams are also a part of the freshwater biome. Because these bodies of water are constantly moving, plant and animal species are extremely diverse, and they vary based on water conditions and temperature.