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Actinopterygii

(Class)

Overview

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The Actinopterygii (), or ray-finned fishes, constitute a class or sub-class of the bony fishes.

The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines ("rays"), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii which also, however, possess lepidotrichia. These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles).

In terms of numbers, actinopterygians are the dominant class of vertebrates, comprising nearly 96% of the 25,000 species of fish. They are ubiquitous throughout fresh water and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 millimetres (0.31 in), to the massive Ocean Sunfish, at 2,300 kilograms (5,100 lb), and the long-bodied Oarfish, to at least 11 metres (36 ft).

Fossil record

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Hypsospondylus fossil

The earliest known fossil Actinopterygiian is Andreolepis hedei, dating back 420 million years (Late Silurian). This microvertebrate has been uncovered in Russia, Sweden, and Estonia.[1]

Classification

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Traditionally three grades of actinopterygians have been recognised: the Chondrostei, Holostei, and Teleostei. Some morphological ev idence suggests that the second is paraphyletic and should be abandoned; however, recent work based on more complete sampling of fossil taxa, and also an analysis of DNA sequence data from the complete mitochondrial genome, supports its recognition. Nearly all living bony fishes are teleosts.

A listing of the different groups is given below, down to the level of orders, arranged in what has been suggested to represent the evolutionary sequence down to the level of order based primarily on the long history of morphological studies. This classification, like any other taxonomy based on phylogenetic research is in a state of flux. Recent morphological and molecular data has shown that several of these ordinal and higher-level groupings represent evolutionary grades rather than clades. Examples of demonstrably paraphyletic groups include the Paracanthopterygii, Scorpaeniformes, and Perciformes.[2] The listing follows FishBase[3] with notes when this differs from Nelson[4] and ITIS.[5]

letic and should be abandoned; however, recent work based on more complete sampling of fossil taxa, and also an analysis of DNA sequence data from the complete mitochondrial genome, supports its recognition. Nearly all living bony fishes are teleosts.

A listing of the different groups is given below, down to the level of orders, arranged in what has been suggested to represent the evolutionary sequence down to the level of order based primarily on the long history of morphological studies. This classification, like any other taxonomy based on phylogenetic research is in a state of flux. Recent morphological and molecular data has shown that several of these ordinal and higher-level groupings represent evolutionary grades rather than clades. Examples of demonstrably paraphyletic groups include the Paracanthopterygii, Scorpaeniformes, and Perciformes.[2] The listing follows FishBase[3] with notes when this differs from Nelson[4] and ITIS.[5]

Notes

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  1. ^ Palaeobase
  2. ^ G. D. Johnson and E. O. Wiley (March 2007). "Tree of Life: Percomorpha". http://www.tolweb.org/Percomorpha/52146. 
  3. ^ R. Froese and D. Pauly (editors) (February 2006). "FishBase". http://www.fishbase.org. 
  4. ^ Nelson, Joseph, S. (2006). Fishes of the World. John Wiley & Sons, Inc.. ISBN 0-471-25031-7. 
  5. ^ "Actinopterygii". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=161061. Retrieved 3 April 2006. 
  6. ^ In Nelson, Polypteriformes is placed in its own subclass Cladistia.
  7. ^ In ITIS, Gobiesociformes is placed as the suborder Gobiesocoidei of the order Perciformes.
  8. ^ In Nelson and ITIS, Syngnathiformes is placed as the suborder Syngnathoidei of the order Gasterosteiformes.

External links

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Taxonomy

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The Class Actinopterygii is further organized into finer groupings including:

Orders

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Acipenseriformes

Acipenseriformes () are an order of primitive ray-finned fishes that includes the sturgeons and paddlefishes, as well as some extinct families. [more]

Amiiformes

Amiiformes is an order of fish, of which only one species, the Bowfin, Amia calva, is still extant. [more]

Atheriniformes

Atheriniformes, also known as the silversides, is an order of ray-finned fish that includes the Old World silversides and several less-familiar families, including the unusual Phallostethidae. They are found worldwide in tropical and temperate marine and freshwater environments. [more]

Aulopiformes

Aulopiformes is an order of marine ray-finned fish consisting of some 15 extant and several prehistoric families with about 45 genera and over 230 species. The common names grinners, lizardfishes and allies or aulopiforms are sometimes used for this group. The scientific name means "Aulopus-shaped", from (the type genus) + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek aul?s (a????, "flute" or "pipe") + Latin forma ("external form"), the former in reference to the elongated shape of many Aulopiformes. [more]

Beloniformes

The Beloniformes are an order of five families of freshwater and marine ray-finned fish: the Adrianichthyidae (ricefish and medakas); Belonidae (needlefish); Exocoetidae (flyingfishes); Hemiramphidae (halfbeaks); and the Scomberesocidae (sauries). With the exception of the Adrianichthyidae, these are streamlined, medium-sized fishes that live close to the surface of the water feeding on algae, plankton, or smaller animals including other fishes. Most are marine, though a few needlefish and halfbeaks inhabit brackish and fresh waters. [more]

Beryciformes

Beryciformes is an order of ray-finned fishes. This is a very poorly understood group of 16 families[], 57 genera, and about 219 species. Some people[who?] believe that it is probably an artificial assemblage of unrelated taxa that are thrown together for convenience only; there are no convincing characteristics that tie all members together. Most species live in deep marine waters, and avoid bright light, although they may come closer to the surface at night. [more]

Characiformes

The Characiformes are an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, there are a few thousand different species, including the well-known piranha and tetras. [more]

Clupeiformes

Clupeiformes is the order of ray-finned fish that includes the herring family, Clupeidae, and the anchovy family, Engraulidae. The group includes many of the most important food fish. [more]

Cypriniformes

The Cypriniformes are an order of ray-finned fish, including the carps, minnows, loaches and relatives. This order contains 5-6 families, over 320 genera, and more than 3,250 species, with new species being described every few months or so, and new genera being recognized regularly. They are most diverse in southeastern Asia, but are entirely absent from Australia and South America. [more]

Ellimmichthyiformes

[more]

Gadiformes

Gadiformes is an order of ray-finned fish, also called the Anacanthini, that includes the cod and its allies. Many major food fish are in this order. They are found in marine waters throughout the world, and there are also a small number of freshwater species. [more]

Gasterosteiformes

Gasterosteiformes is an order of ray-finned fishes that includes the sticklebacks and relatives. [more]

Gonorhynchiformes

[more]

Ichthyodectiformes

[more]

Lampridiformes

Lampriformes is an order of ray-finned fish. They are collectively called "lamprids" (which is more properly used for the Lampridae) or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opahs and ribbonfishes. A synonym for this order is Allotriognathi, while an often-seen but apparently incorrect spelling variant is Lampridiformes. They contain 7 extant families which are generally small but highly distinct, and a mere 12 lampriforms genera with some 20 species altogether are recognized. [more]

Ophidiiformes

Ophidiiformes is an order of ray-finned fish that includes the cusk eels (family Ophidiidae), pearlfishes (family Carapidae), brotulas (family Bythitidae), and others. [more]

Osmeriformes

Osmeriformes is an order of ray-finned fish that includes the true or freshwater smelts and allies, such as the galaxiids and noodlefishes; they are also collectively called osmeriforms. They belong to the teleost superorder Protacanthopterygii, which also includes pike and salmon, among others. The order's name means "smelt-shaped", from Osmerus (the type genus) + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek osm? (?s??, "pungent smell") + Latin forma ("external form"), the former in reference to the characteristic aroma of the flesh of Osmerus. [more]

Osteoglossiformes

Osteoglossiformes (Gk. "bony tongues") is a relatively primitive order of ray-finned fish that contains two sub-orders, the Osteoglossoidei and the Notopteroidei. All of the living species inhabit freshwater. They are found in South America, Africa, Australia and southern Asia, having first evolved in Gondwana before that continent broke up. [more]

Palaeonisciformes

[more]

Perciformes

Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means "perch-like". They belong to the class of ray-finned fish, and comprise over 7,000 species found in almost all aquatic environments. It contains about 155 families, which is the most of any order within the vertebrates. They are also the most variably sized order of vertebrates, ranging from the 7 millimeters (0.28 in) Schindleria brevipinguis to the 5 meters (16 ft) Makaira species. They first appeared and diversified in the Late Cretaceous. Among well-known members of this group are cichlids, sunfish/bluegill, damselfish, bass, and, of course, perch. [more]

Pleuronectiformes

The flatfish are an order (Pleuronectiformes) of ray-finned demersal fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development. Some species face their left side upward, some face their right side upward, and others face either side upward. [more]

Scorpaeniformes

Scorpaeniformes is an order of ray-finned fish, but it has also been called the Scleroparei. [more]

Siluriformes

Catfishes (order Siluriformes) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores (species that eat dead material on the bottom), and even to a tiny parasitic species commonly called the candiru, Vandellia cirrhosa. There are armour-plated types and also naked types, neither having scales. Despite their name, not all catfish have prominent barbels; members of the Siluriformes order are defined by features of the skull and swimbladder. Catfish are of considerable commercial importance; many of the larger species are farmed or fished for food. Many of the smaller species, particularly the genus Corydoras, are important in the aquarium hobby. Catfish are nocturnal. [more]

Stomiiformes

Stomiiformes is an order of deep-sea ray-finned fishes of very diverse morphology. It includes for example dragonfishes, lightfishes, loosejaws, marine hatchetfishes and viperfishes. The order contains 4 families (5 according to some authors) with more than 50 genera and almost 400 species. As usual for deep-sea fishes, there are few common names for species of the order, but the Stomiiformes as a whole are often called dragonfishes and allies or simply stomiiforms. [more]

Tetraodontiformes

The Tetraodontiformes are an order of highly derived ray-finned fish, also called the Plectognathi. Sometimes these are classified as a suborder of the Perciformes. The Tetraodontiformes are represented by ten families and approximately 360 species overall; most are marine and dwell in and around tropical coral reefs, but a handful of species are found in freshwater streams and estuaries. They have no close relatives, and descend from a line of coral-dwelling species that emerged around 40 million years ago. [more]

Zeiformes

The Zeiformes are a small order of marine ray-finned fishes most notable for the dories, a group of common food fish. The order consists of about 40 species in seven families, mostly deep-sea types. [more]

At least 89 species and subspecies belong to the Order Zeiformes.

More info about the Order Zeiformes may be found here.

Footnotes

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  1. ^ Palaeobase
  2. ^ G. D. Johnson and E. O. Wiley (March 2007). "Tree of Life: Percomorpha". http://www.tolweb.org/Percomorpha/52146. 
  3. ^ R. Froese and D. Pauly (editors) (February 2006). "FishBase". http://www.fishbase.org. 
  4. ^ Nelson, Joseph, S. (2006). Fishes of the World. John Wiley & Sons, Inc.. ISBN 0-471-25031-7. 
  5. ^ "Actinopterygii". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=161061. Retrieved 3 April 2006. 
  6. ^ In Nelson, Polypteriformes is placed in its own subclass Cladistia.
  7. ^ In ITIS, Gobiesociformes is placed as the suborder Gobiesocoidei of the order Perciformes.
  8. ^ In Nelson and ITIS, Syngnathiformes is placed as the suborder Syngnathoidei of the order Gasterosteiformes.

Sources

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Last Revised: August 24, 2012
2012/08/24 13:05:16