Teleostei

Teleost Temporal range: Early Triassic–Recent PreЄ Є O S D C P T J K Pg N
Painted by Castelnau, 1856 (left to right, top to bottom): Fistularia tabacaria, Mylossoma duriventre, Mesonauta acora, Corydoras splendens, Pseudacanthicus spinosus, Acanthurus coeruleus, Stegastes pictus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Subclass:	Neopterygii
Infraclass:	Teleostei Müller, 1845
Subdivisions
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The teleosts or Teleostei (Greek: teleios, "complete" + osteon, "bone") are by far the largest infraclass in the class Actinopterygii, the ray-finned fishes, and make up 96 percent of all fish. This diverse group arose in the Triassic period and members are arranged in about 40 orders and 448 families. Over 26,000 species have been described. Teleosts range from giant oarfish, measuring 25 ft (7.6 m) or more, and ocean sunfish weighing over 2.0 long tons; 2.2 short tons (2 t), to the minute male anglerfish , just 0.24 in (6.2 mm) long. As well as torpedo-shaped fish built for speed, teleosts can be flattened vertically or horizontally, be elongated cylinders or take specialised shapes as in anglerfish and seahorses. Teleosts dominate the seas from pole to pole and inhabit the ocean depths, estuaries, rivers, lakes and even swamps.

The difference between teleosts and other bony fish lies mainly in their jaw bones; teleosts have a movable premaxilla and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth. This is of great advantage, enabling them to grab prey and draw it into the mouth. In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling the premaxilla as the mouth is opened and closed. Other bones further back in the mouth serve to grind and swallow food. Another difference is that the upper and lower lobes of the tail (caudal) fin are about equal in size. The spine ends at the caudal peduncle, distinguishing this group from other fish in which the spine extends into the upper lobe of the tail fin.