Clear, often nutrient-poor waters, far from shore
Tunas, seabirds, dolphins, billfishes, flyingfishes, jellyfishes, deep-sea fishes
Fisheries, oxygen production, climate regulation
Many species that live in the open ocean (or pelagic realm) truly live in an ocean universe. More than 70% of the Earth’s surface is covered by ocean, and it is important to remember that more than 50% of the Earth’s surface is covered by ocean that is at least two miles (3.2 km) deep! Many open ocean organisms live out their existence without ever coming into contact with the shore, the seafloor, or the water’s surface. They spend their entire lives surrounded by water on all sides and do not know that anything else even exists. In the case of the deep open ocean, organisms never even see sunlight. As land mammals that breathe air, walk on land, and rely on our sense of sight for almost all functions, it is difficult for people (even experts) to comprehend that most of the organisms on the planet are never exposed to air, land, or sunlight.
The open ocean is an enormous place. In fact, more than 90% of the inhabitable space on earth is in the open ocean. In order to better study and understand this huge ecosystem, scientists divide the it into different zones:
Finally, organisms that live on the ocean floor (regardless of depth) are part of the benthos. Benthic ecosystems include coral reefs, seagrass beds, and other systems in shallow coastal areas and deep hydrothermal vents, the abyssal plain, and other systems in the deep sea.