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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 ...
Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. [2] Ascidians are characterized by a tough outer "tunic" made of a polysaccharide. Ascidians are found all over the world, usually in shallow water with salinities over 2.5%.
Invoking images of the open ocean's surface, the imagination can conjure up an endless empty space. A flat line parting the blue below from the blue above. But in reality a diverse array of species occupy this unique boundary layer. A tangle of terms exist for different organisms occupying different niches of the ocean's surface.
Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply [1] [2] and 90% of habitable space on Earth. [3] Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. [4]
Marine biology is the scientific study of the biology of marine life, organisms that inhabit the sea.Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.
Gills or gill-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians. Semiterrestrial marine animals such as crabs and mudskippers have gill chambers in which they store water, enabling them to use the dissolved oxygen when they are on land.
Phytoplankton (/ ˌ f aɪ t oʊ ˈ p l æ ŋ k t ə n /) are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems.The name comes from the Greek words φυτόν (phyton), meaning 'plant', and πλαγκτός (planktos), meaning 'wanderer' or 'drifter'.
Oceanic nekton comprises aquatic animals largely from three clades: Vertebrates (phylum Chordata), particularly pelagic fish, cetaceans and sea turtles, form the largest contribution; these animals have endoskeletons made of bones and cartilages and propel themselves via a powerful tail and fan/paddle-shaped appendages such as fins, flippers or ...