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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).
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 ...
The pilot fish congregates around sharks, rays, and sea turtles, where it eats ectoparasites on, and leftovers around, the host species; [4] younger pilot fish are usually associated with jellyfish and drifting seaweeds. [5] They are also known to follow ships, sometimes for long distances; one was found in County Cork, Ireland, [6] and many ...
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 ...
A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
Sharks are cartilaginous fish. The skeleton of a shark is mainly made of cartilage. They belong to the class of Chondrichthyes. In particular, the endoskeletons are made of unmineralized hyaline cartilage which is more flexible and less dense than bone, thus making them expel less energy at high speeds.
Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, compose the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the ...
Elasmobranchii (/ ɪˌlæzməˈbræŋkiaɪ / [6]) is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks (superorder Selachii), rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins ...