Oceans are vast bodies of water that cover roughly 70% of the earth. Seas are smaller and partially enclosed by land. The five oceans of the earth are in reality one large interconnected water body. In contrast, there are over 50 smaller seas scattered around the world.
Oceans cover 71% of the Earth's surface, and contain 97 percent of the planet's water. The Pacific Ocean is the largest ocean covering an area of 64,186,000 square miles and the Mediterranean Sea is the largest sea with an area of 1,144,800 square miles. In fact even the world’s smallest ocean Arctic Ocean (5,427,000 square miles) is larger than the Mediterranean.
edit List of oceans by size
- Pacific Ocean: 60,060,700 square miles
- Atlantic Ocean: 29,637,900 square miles
- Indian Ocean: 26,469,900 square miles
- Southern Ocean: 7,848,300 square miles
- Arctic Ocean: 5,427,000 square miles
edit Top 6 largest seas
- Mediterranean Sea: 1,144,800 square miles
- Caribbean Sea: 1,049,500 square miles
- South China Sea: 895,400 square miles
- Bering Sea: 884,900 square miles
- Gulf of Mexico: 615,000 square miles
- Okhotsk Sea: 613,800 square miles
The average depth in oceans is from 3,953ft to 15,215ft. Mariana Trench in the Pacific Ocean is the deepest, 36,200 ft deep. At 22,788 ft, the Caribbean Sea is the deepest sea. Most seas are much shallower.
edit Marine life
Oceans and seas are home to rich and diverse marine life. The depth and distance from shore strongly influence the quantity and biodiversity of the plants and animals that live there. As seas are always near land marine life are abundant while oceans which are deeper and farther away from land have on few basic life forms like bacteria, microscopic plankton and shrimp.
Porpoises have a triangular dorsal fin
Any water in a sea, ocean or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. Areas in the pelagic zone are distinguished by their depth and the ecology of the zone. It is further divided into:
- The epipelagic zone (sunlit) is closest to the surface and stretches down to around 200 m. An abundance of light allows for photosynthesis by plants and nutrients for animals like tuna external and sharks.
- The mesopelagic zone (twilight) begins at 200 m below the surface and reaches a depth of 1,000 m. There is a little light but not enough for photosynthesis to occur.
- The bathypelagic zone (midnight) follows, from 1000-4,000 m in depth. Bioluminescent organisms are found in this zone. Unique animals like the marine hatchet fish external and giant squid live in this zone, surviving mostly on the detritus that drifts down from the epipelagic zone.
- The abyssopelagic zone (lower midnight) is located from 4,000 m to directly above the ocean floor and is a completely dark area home to colorless and blind animals.
- The Hadopelagic zone is the deep water in ocean trenches. Some define the hadopelagic as waters below 6,000 m (19,685 ft), whether in a trench or not. Very little is known about this zone, and very few species are known to live here.
The bathypelagic, abyssopelagic, and hadopelagic zones are very similar in character, and some marine biologists combine them into a single zone or consider the latter two to be the same. The abyssal plain is covered with soft sludge composed of dead organisms from above.
Ocean currents greatly affect the Earth's climate by transferring heat from the tropics to the Polar Regions, and transferring warm or cold air and precipitation to coastal regions. People living in coastal areas (near a sea) experience humid weather.