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Pelagic zones. The ocean can be conceptualized as being divided into various zones, depending on depth, and presence or absence of sunlight.Nearly all life forms in the ocean depend on the photosynthetic activities of phytoplankton and other marine plants to convert carbon dioxide into organic carbon, which is the basic building block of organic matter.
Marine life, sea life or ocean life is the collective ecological communities that encompass all aquatic animals, plants, algae, fungi, protists, single-celled microorganisms and associated viruses living in the saline water of marine habitats, either the sea water of marginal seas and oceans, or the brackish water of coastal wetlands, lagoons ...
Another advantage of living in a group is seen in many prey species in their ability to increase defenses against predatory animals. A way that a group may increase its defenses against predators is through the ‘many-eyes effect’. This effect states that larger groups of animals are better at detecting predators compared to smaller groups. [15]
Aquatic animals generally conduct gas exchange in water by extracting dissolved oxygen via specialised respiratory organs called gills, through the skin or across enteral mucosae, although some are evolved from terrestrial ancestors that re-adapted to aquatic environments (e.g. marine reptiles and marine mammals), in which case they actually ...
Organisms that live freely at the ocean surface, termed neuston, include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, marine snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston.
In the wild, females who survive infancy live 46 years on average, and up to 70–80 years in rare cases. Wild males who survive infancy live 31 years on average, and up to 50–60 years. [ 149 ] Captivity usually bears little resemblance to wild habitat, and captive whales' social groups are foreign to those found in the wild.
Sauropterygians were a diverse group of aquatic reptiles adapted for flipper-based aquatic locomotion. This group included the plesiosaurs, nothosaurs, and placodonts. Mosasaurs were a group of large, aquatic squamates (relatives of modern-day lizards and snakes) which became the dominant marine predators towards the end of the Cretaceous period.
Marine invertebrates are animals that inhabit a marine environment apart from the vertebrate members of the chordate phylum; invertebrates lack a vertebral column. Some have evolved a shell or a hard exoskeleton. The earliest animals may belong to the genus Dickinsonia, [2] 571 million to 539 million years ago. [3]