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Fish vision shows adaptation to their visual environment, for example deep sea fishes have eyes suited to the dark environment. Fish and other aquatic animals live in a different light environment than terrestrial species. Water absorbs light so that with increasing depth the amount of light available decreases quickly.
Evolution of fish. The Devonian period (419–359 Mya), also known as the Age of Fishes, saw the development of early sharks, armoured placoderms and various lobe-finned fish, including the tetrapod transitional species. The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early ...
Organisms at high altitude. An Alpine chough in flight at 3,901 m (12,799 ft) Organisms can live at high altitude, either on land, in water, or while flying. Decreased oxygen availability and decreased temperature make life at such altitudes challenging, though many species have been successfully adapted via considerable physiological changes.
Ray finned species, with spiny fins, are rare among deep sea fishes, which suggests that deep sea fish are ancient and so well adapted to their environment that invasions by more modern fishes have been unsuccessful. [18] The few ray fins that do exist are mainly in the Beryciformes and Lampriformes, which also are ancient forms. Most deep sea ...
Climate change is modifying fish distributions [ 6] and the productivity of marine and freshwater species. Climate change is expected to lead to significant changes in the availability and trade of fish products. [ 7] The geopolitical and economic consequences will be significant, especially for the countries most dependent on the sector.
Fish locomotion. Fish locomotion is the various types of animal locomotion used by fish, principally by swimming. This is achieved in different groups of fish by a variety of mechanisms of propulsion, most often by wave-like lateral flexions of the fish's body and tail in the water, and in various specialised fish by motions of the fins.
But even so, there can be unusual adaptations. Four-eyed fish have eyes raised above the top of the head and divided in two different parts, so that they can see below and above the water surface at the same time. Four-eyed fish actually have only two eyes, but their eyes are specially adapted for their surface-dwelling lifestyle.
Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many ways, especially the difference in levels of osmolarity. To survive in fresh water, fish need a range of ...