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Fish anatomy. Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. [1] In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or ...
The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys.
Fish gill. Gill arches bearing gills in a pike. Gills allow fish to breathe underwater. Respiratory mechanism in bony fish. The fish draws oxygen-rich water in through the mouth (left). It then pumps it over gills so oxygen enters the bloodstream, and allows oxygen-depleted water to exit through the gill slits (right) Fish gills are organs that ...
External gills. External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill of stalks protruding from the sides of an animal's head. The axolotl has three ...
Chondrichthyes (/ kɒnˈdrɪkθiiːz /; from Ancient Greek χόνδρος (khóndros) 'cartilage' and ἰχθύς (ikhthús) 'fish') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or bony fish, which have ...
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After 2 to 3 months the young transform (called metamorphosis) into the adult form, losing the external gills for gill openings. These fish have a yellowish gray or pinkish toned ground color with dark slate-gray splotches, creating a marbling or leopard effect over the body and fins. The color pattern is darker along the top and lighter below ...
Shark. † Synechodontiformes. Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha[1] (or Selachii) and are the sister group to the Batoidea (rays and kin).