- Tetraodontiformes
Taxobox
name = Tetraodontiformes
image_caption =American whitespotted filefish , "Cantherhines macrocerus"
regnum =Animal ia
phylum = Chordata
classis =Actinopterygii
ordo = Tetraodontiformes
subdivision_ranks = Families
subdivision = See text.The Tetraodontiformes are an order of highly derived ray-finned fish, also called the Plectognathi. Sometimes these are classified as a
suborder of thePerciformes . The Tetraodontiformes are represented by ten families and approximately 360species overall; most are marine and dwell in and around tropicalcoral reef s, but a handful of species are found in freshwater streams and estuaries. They have no close relatives, and descend from a line ofcoral -dwelling species that emerged around 40 million years ago.Physical characteristics
Various bizarre forms are included here, all radical departures from the streamlined body plan typical of most fishes. These forms range from nearly square or triangular (
boxfish es), globose (pufferfish es) to laterally compressed (filefish es). They are ostraciiforms, meaning the body is inflexible, and undulation during movement is limited to the caudal fin. Because of this, they are slow-moving and rely on their pectoral and caudal fins for propulsion. However, movement is usually quite precise; dorsal and anal fins aid in manoeuvring and stabilizing. In most species, all fins are simple, small, and rounded.The tetraodontiform strategy seems to be defense at the expense of speed, with all species fortified with scales modified into strong plates or spines — the latter sometimes retractable and able to lock in place (the
triggerfish es) — or with tough, leathery skin (thefilefish es andocean sunfish ). Another striking defensive attribute found in thepufferfish es andporcupinefish es is the ability to inflate the body to greatly increase its normal diameter: this is accomplished by sucking water into adiverticulum of thestomach . Many species of theTetraodontidae ,Triodontidae andDiodontidae are further protected from predation bytetraodotoxin , a powerfulneurotoxin concentrated in the animals' internal organs.Tetraodontiforms have highly modified
skeleton s, with no nasal, parietal, infraorbital, or (usually) lowerrib bones. The bones of the jaw are modified and fused into a sort of "beak "; there are visible sutures which divide the beaks into "teeth". This is alluded to in their name, derived from the Greek words "tetra" meaning "four" and "odous" meaning "tooth" and theLatin "forma" meaning "shape". Counting these teeth-like bones is a way of distinguishing similar families. For example the Tetraodontidae ("four-toothed"), Triodontidae ("three-toothed"), and Diodontidae ("two-toothed").The jaws are aided by powerful muscles and many species also have pharyngeal teeth to further process prey items. This is because Tetraodontiformes prey mostly on hard-shelled
invertebrate s such ascrustacean s andshellfish .The
Molidae are conspicuous even within this oddball order: they lackswim bladder s and spines, and are propelled by their very tall dorsal and anal fins. The caudal peduncle is absent and the caudal fin is reduced to a stiff rudder-like structure. Molids are pelagic rather than reef-associated and feed on soft-bodied invertebrates, especiallyjellyfish .Families
*
Aracanidae
*Balistidae —triggerfish es
*Diodontidae —porcupinefish es
*Molidae —ocean sunfish and relatives
*Monacanthidae —filefish es
*Ostraciidae —boxfish es
*Tetraodontidae —pufferfish es
*Triacanthidae —triplespine s
*Triacanthodidae —spikefish es
*Triodontidae —three-toothed puffer Fossil families
* †
Bolcabalistidae
* †Cretatriacanthidae
* †Eoplectidae
* †Eospinidae
* †Moclaybalistidae
* †Plectocretacicidae
* †Protobalistidae
* †Protriacanthidae
* †Spinacanthidae References
*
References
* [http://tolweb.org/Tetraodontiformes/52153 Tree of Life: Tetraodontiformes]
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