The open ocean

[...]... of the Ocean Floor Although the average ocean depth is 12,179 feet (3,700 m), the deep ocean includes waters ranging from 656 feet (200 m) to 36,213.9 feet (11,038 m) As shown in Figure 1.1, the profile of the deep ocean floor begins where the edges of the continents drop off sharply in depth The incline of this steep 1 2 T The Open Ocean Fig 1.1 The continental shelf begins a downward slant at the. .. level Other low points include the Peru-Chile Trench, which runs along the entire west coast of South America, the Japan-Kuril Trench near Japan, and the Aleutian Trench off the Aleutian Islands in the Pacific Ocean In the Atlantic Ocean, there are two, relatively short trenches: the South Sandwich Trench, below the southernmost tip of South America, and the Puerto Rico–Cayman Trench, between the southeastern... slide from the tops to the bases of the slopes At the bottom of the continental slope is the continental rise, a gentle incline composed of accumulations of sediment The Atlantic Ocean contains more continental rises than the Pacific Ocean because, in the latter, there are many deep trenches at the base of slopes Continental rises are also found around Antarctica and in the Indian Ocean Beyond the continental... playing the roles that plants perform in terrestrial and shallow-water systems In the upper layers of the ocean where the Sun is the source of energy, primary producers are organisms that can carry out photosynthesis Most of the photosynthetic cells in the oceanic realm live in the photic zone as members of the plankton The term plankton, derived from the Greek for “wanderer” or “drifter,” describes the. .. about the physical and chemical conditions of the water and many of the organisms that live there However, the difficulties of exploring the vast and remote areas make the deep ocean a frontier that still needs to be better understood The deep seafloor begins at the point where the continental slope plunges downward At the base of the slope, a gentle incline called the continental rise results from the. .. do not move around but get their food by converting the Sun’s energy into simple carbon compounds Therefore, plants are autotrophs Animals, on the other hand, cannot make their own food These organisms are heterotrophs, and they include fish, whales, and humans, all of which must actively seek the food they eat 19 20 T The Open Ocean Conclusion Even though the deep sea is the Earth’s largest habitat,... 1 Aspects rPhysicaland Chemistry of the Open Ocean Light, Depth, he majority of the sea, the portion referred to as the deep, open ocean, lies beyond the relatively shallow waters of the continental shelves Covering more than 50 percent of the Earth’s surface, this watery universe is the planet’s largest habitat No one knows for sure how many organisms live in the open sea, but scientists estimate that... northeastern South America 3 4 T The Open Ocean Dividing Waters To help define marine environments, scientists divide the water column and the ocean floor into zones Even though these zones lack sharp boundaries, they aid in the study of the ocean and its inhabitants Each zone displays unique chemical, physical, and biological characteristics Two broad areas of surface water are the neritic zone and the. .. Below the dysphotic zone is the aphotic zone, 1,640.4 feet (500 m) and deeper, where the water is completely dark The animals that live in the dysphotic and aphotic zones either feed on food that floats down from the upper layers or travel to the upper layers to get food Although sunlight is plentiful in the upper layers of the open ocean, populations of photosynthetic organisms are relatively small The. .. waters sink to the seafloor, supplying oxygen to the organisms that live in the lowest depths Even though oxygen in the deepest regions of the sea is constantly consumed by animals and other organisms, it is never completely depleted In the upper levels of the ocean, there is always plenty of oxygen Two sources keep the surface waters well supplied with the gas: the air and plants Oxygen gas in the atmosphere . living things make their homes there. Less is known about the deep and open portions of the ocean than of any other area of the planet. The very magni- tude of these waters has made them as difficult. shelves. Chapter 1 examines the features of the ocean floor as well as the vertical zones of the ocean, each zone defined by depth. The three-dimensional aspect of the oceanic world makes life there very different. shore, but the average sea surface temperature (SST) of the open ocean is about 6 The T Open Ocean 62.6°F (17°C). Because the temperature of water changes very gradually, in some parts of the ocean,