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Fish have a variety of different body plans. At the broadest level, their body is divided into the head, trunk, and tail, although the divisions are not always externally visible. The body is often fusiform , a streamlined body plan often found in fast-moving fish.
Fish fins are distinctive anatomical features with varying structures among different clades: in ray-finned fish (Actinopterygii), fins are mainly composed of bony spines or rays covered by a thin stretch of scaleless skin; in lobe-finned fish (Sarcopterygii) such as coelacanths and lungfish, fins are short rays based around a muscular central ...
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.
Common names of fish can refer to a single species; to an entire group of species, such as a genus or family; or to multiple unrelated species or groups. Ambiguous common names are accompanied by their possible meanings. Scientific names for individual species and higher taxa are included in parentheses.
Selective breeding over centuries has produced several color variations, some of them far removed from the "golden" color of the original fish. There are also different body shapes, fin, and eye configurations. Some extreme versions of the goldfish live only in aquariums—they are much less hardy than varieties closer to the "wild" original.
Osteichthyes (/ ˌ ɒ s t iː ˈ ɪ k θ iː z / ost-ee-IK-theez), [2] also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue.
The skeleton of the head of a perch Parts of a pike's head. 1: liver, 2: gill arch, 3: palate with sharp teeth, 4: in the middle a heart, 5: fragment of spinal cord, 6: brain, 7: spherical lens, 8: scale
The term "fish" describes any non-tetrapod chordate, (i.e., an animal with a backbone), that has gills throughout life and has limbs, if any, in the shape of fins. [8] Unlike groupings such as birds or mammals, fish are paraphyletic, since the tetrapod clade is within the clade of lobe-finned fishes. [9] [10]