Teleostei (redirected from teleost)

Teleostei [‚tel·ē′äs·tē‚ī]

(vertebrate zoology)

An infraclass of the subclass Actinopterygii, or rayfin fishes; distinguished by paired bracing bones in the supporting skeleton of the caudal fin, a homocercal caudal fin, thin cycloid scales, and a swim bladder with a hydrostatic function.

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Teleostei 

a superorder of fish. Teleosts have a bony skeleton, amphicoelous (biconcave), vertebrae, and a skull with strongly developed ossifications. The body length ranges from 1 cm (some gobies) to 5 m (catfish, barracuda, swordfish, tuna). Cycloid or ctenoid scales with either little spines or bony plates cover the body; some teleosts are scaleless. The majority of these fish have scales without a ganoin (the ganoin is found only in the scales of fossil Leptolepoidei of the order Clupeiformes). Teleosts usually have a homocercal fin; some have a diphycercal fin. Most of the fish have a bulbus arteriosus; the most ancient (teleosts of the families Megalopidae and Albulidae) have retained the conus arteriosus.

Teleosts first appeared in the middle Triassic period. They have now reached their highest development, comprising approximately 40 orders. More than 90 percent of all modern species are included in the superorder. Teleosts are found in all bodies of water that support fish life. They are sexually dimorphic, with only a few hermaphrodites (for example, Serranus scriba). Fertilization is usually external, with the fish depositing their eggs; some species are characterized by internal fertilization and bring forth young alive (Baikal oil-fish, mosquito fish, and others). Some teleosts are herbivorous, some are carnivorous, and some parasitize other fish (the eel Simenchelys parasiticus and Stegophilus insidiosus). Almost all of the principal commercial fish belong to the superorder Teleostei, accounting for more than 98 percent of the world catch.

REFERENCES

Berg, L. S. Sistema ryboobraznykh ryb, nyne zhivushchikh i iskopaemykh, 2nd ed. Moscow-Leningrad, 1955. (Trudy Zoologicheskogo in-ta, vol. 20.)
Berg, L. S. Ryby presnykh vod SSSR i sopredel’nykh stran, 4th ed., parts 1–3. Moscow-Leningrad, 1948–49.
Nikol’skii, G. V. Chastnaia ikhtiologiia, 3rd ed. Moscow, 1971.

G. V. NIKOL’SKII