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Aquatic respiration is the process whereby an aquatic organism exchanges respiratory gases with water, obtaining oxygen from oxygen dissolved in water and excreting carbon dioxide and some other metabolic waste products into the water.
The pelagic food web, showing the central involvement of marine microorganisms in how the ocean imports nutrients from and then exports them back to the atmosphere and ocean floor. A marine food web is a food web of marine life. At the base of the ocean food web are single-celled algae and other plant-like organisms known as phytoplankton.
A current of water is maintained through the gills for gas exchange, and food particles are filtered out at the same time. These may be trapped in mucus and moved to the mouth by the beating of cilia. [16] Respiration in the echinoderms (such as starfish and sea urchins) is carried out using a very primitive version of gills called papulae.
Oxygen in the surface ocean is continuously added across the air-sea interface as well as by photosynthesis; it is used up in respiration by marine organisms and during the decay or oxidation of organic material that rains down in the ocean and is deposited on the ocean bottom.
Altogether the ocean occupies 71 percent of the world surface, [4] averaging nearly 3.7 kilometres (2.3 mi) in depth. [27] By volume, the ocean provides about 90 percent of the living space on the planet. [4] The science fiction writer Arthur C. Clarke has pointed out it would be more appropriate to refer to planet Earth as planet Ocean. [28] [29]
The tiny (0.6 μm) marine cyanobacterium Prochlorococcus, discovered in 1986, forms today an important part of the base of the ocean food chain and accounts for much of the photosynthesis of the open ocean [84] and an estimated 20% of the oxygen in the Earth's atmosphere. [85]
A rarely seen deep sea fish resembling a serpent was found floating dead on the ocean surface off the San Diego coast and was brought ashore for study, marine experts said. The silvery, 12-foot ...
Many commercial and subsistence fisheries in arctic and subarctic regions fish for cod, salmon, crab, groundfish, and pollock depend on this energy-rich zooplankton as food. [ 20 ] [ 5 ] In 2017, the highest value of commercial fish species for the US was salmon ($688 million), crabs ($610 million), shrimp ($531 million), scallops ($512 million ...