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Vision is an important sensory system for most species of fish. Fish eyes are similar to those of terrestrial vertebrates like birds and mammals, but have a more spherical lens. Their retinas generally have both rod cells and cone cells (for scotopic and photopic vision), and most species have colour vision.
Fish physiology is the scientific study of how the component parts of fish function together in the living fish. [ 2 ] It can be contrasted with fish anatomy, which is the study of the form or morphology of fishes. In practice, fish anatomy and physiology complement each other, the former dealing with the structure of a fish, its organs or ...
Aquatic respiration. Sea slugs respire through a gill (or ctenidium) 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.
Conversely, freshwater has less osmolytes than the fish's internal fluids. Therefore, freshwater fishes must utilize their gill ionocytes to attain ions from their environment to maintain optimal blood osmolarity. [6] [10] In some primitive bony fishes and amphibians, the larvae bear external gills, branching off from the gill arches. [11]
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 ...
The American paddlefish (Polyodon spathula), also known as a Mississippi paddlefish, spoon-billed cat, or spoonbill, is a species of ray-finned fish. It is the last living species of paddlefish (Polyodontidae). This family is most closely related to the sturgeons; together they make up the order Acipenseriformes, which are one of the most ...
[53] [55] This is to compensate for the low oxygen environment. This adaptation is associated with developmental patterns such as high birth weight, increased lung volumes, increased breathing, and higher resting metabolism. [56] [57] The genome of Tibetans provided the first clue to the molecular evolution of high-altitude adaptation in 2010. [58]
Within cartilaginous fish, approximately 80% of the sharks, rays, and skates families survived the extinction event, [114] and more than 90% of teleost fish (bony fish) families survived. [115] There is evidence of a mass kill of bony fishes at a fossil site immediately above the K–T boundary layer on Seymour Island near Antarctica ...