Actinopterygii

Ray-finned fish
Fossil range: Late Silurian–Recent
Atlantic herring
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclass: Osteichthyes
Class: Actinopterygii
Klein, 1885
Subclasses

Chondrostei
Neopterygii

The Actinopterygii constitute the class or sub-class of the ray-finned 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 95% 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).

Contents

Fossil record

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

Traditionally three grades of actinopterygians have been recognised: the Chondrostei, Holostei, and Teleostei. Some morphological evidence 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. Many of these ordinal and higher-level groupings have not been supported in both the recent morphological and molecular literature. Examples of demonstrably paraphyletic or unnatural 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

  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 0471250317. 
  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

Extant Chordata classes by subphylum
Kingdom Animalia · Subkingdom Eumetazoa · (unranked) Bilateria · Superphylum Deuterostomia
Urochordata (Tunicates)
Ascidiacea (Ascidians) · Thaliacea · Appendicularia (Larvaceans) · Sorberacea
Cephalochordata (Lancelets)
Leptocardii
Craniata
Extant Actinopterygii orders by subclass
Kingdom Animalia · Phylum Chordata · Subphylum Vertebrata · Infraphylum Gnathostomata · Superclass Osteichthyes
Chondrostei
Polypteriformes · Acipenseriformes
Neopterygii
Lepisosteiformes · Amiiformes · Osteoglossiformes · Hiodontiformes · Elopiformes · Albuliformes · Notacanthiformes · Anguilliformes · Saccopharyngiformes · Clupeiformes · Gonorynchiformes · Cypriniformes · Characiformes · Gymnotiformes · Siluriformes · Salmoniformes · Esociformes · Osmeriformes · Ateleopodiformes · Stomiiformes · Aulopiformes · Myctophiformes · Lampriformes · Polymixiiformes · Percopsiformes · Batrachoidiformes · Lophiiformes · Gadiformes · Ophidiiformes · Mugiliformes · Atheriniformes · Beloniformes · Cetomimiformes · Cyprinodontiformes · Stephanoberyciformes · Beryciformes · Zeiformes · Gasterosteiformes · Syngnathiformes · Synbranchiformes · Tetraodontiformes · Pleuronectiformes · Scorpaeniformes · Perciformes