The ocean biome is a vast, interconnected aquatic environment encompassing all saltwater bodies on Earth. As the planet’s largest biome, covering a significant portion of its surface, its sheer scale makes it a fundamental component of Earth’s global systems. Understanding its location involves recognizing its extensive global reach and its specific divisions, both horizontally across the planet and vertically through its depths.
Worldwide Presence of the Ocean Biome
The ocean biome forms a continuous body of saltwater that envelops the Earth. It covers approximately 70% to 71% of the planet’s surface, truly making Earth an “ocean world.” This expansive aquatic domain serves as the largest habitat on the planet, playing a role in connecting continents and influencing global climate patterns by facilitating the transfer of heat and moisture around the globe.
Major Ocean Divisions
The ocean biome is conventionally divided into five major ocean basins:
The Pacific Ocean, the largest and deepest, stretches from the Arctic to the Southern Ocean, bordered by the Americas, Asia, and Australia. Its vastness means it covers more area than all Earth’s land combined.
The Atlantic Ocean, the second largest, separates Europe and Africa from the Americas, extending from the Arctic to the Southern Ocean.
The Indian Ocean, the third largest, is primarily in the Southern Hemisphere, bordered by Eastern Africa, the Arabian Peninsula, Southern Asia, and Australia.
Encircling Antarctica, the Southern Ocean is the fourth-largest, characterized by its cold, circumpolar waters.
The Arctic Ocean is the smallest and shallowest, located around the North Pole, surrounded by North America, Europe, and Asia.
Depth-Based Ocean Zones
Beyond its horizontal spread, the ocean biome has distinct vertical “locations” defined by depth and light penetration. The water column is the pelagic zone, while the seafloor is the benthic zone. Within the pelagic zone, varying conditions lead to several layers.
The uppermost layer is the photic or epipelagic zone, extending from the surface down to approximately 200 meters (656 feet). This zone receives sufficient sunlight for photosynthesis, supporting a wide array of marine life. Below this is the mesopelagic zone, or “twilight zone,” ranging from 200 to 1,000 meters (656 to 3,280 feet) deep, where some light penetrates but is insufficient for photosynthesis.
Deeper still is the bathypelagic zone, or “midnight zone,” spanning from 1,000 to 4,000 meters (3,280 to 13,100 feet), characterized by complete darkness. The abyssalpelagic zone, or abyssal zone, lies between 4,000 and 6,000 meters (13,100 to 20,000 feet). The deepest parts are in the hadalpelagic zone, or hadal zone, which includes waters within oceanic trenches, extending from 6,000 meters down to nearly 11,000 meters (36,000 feet) in the Mariana Trench. These vertical zones illustrate the environmental changes that occur with increasing depth, creating diverse habitats.