Characiformes
From Wikipedia, the free encyclopedia
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 Brycinus longipinnis
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Acestrorhynchidae |
The Characiformes are an order of ray-finned fish, comprising the characins and their allies. There are a few thousand different species, including the well-known piranha and tetras.
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[edit] Taxonomy
Originally the characins were all grouped within a single family, the Characidae, which was included in the Cypriniformes. Since then about 15 different families have been separated out. However, classification varies somewhat, and it appears the circumscribed Characidae are still polyphyletic.
Currently, there are eighteen families, about 270 genera, and at least 1674 species.
Characiformes is the sister group to the orders Siluriformes and Gymnotiformes.
[edit] Anatomy
These belong within the superorder Ostariophysi, a group mainly distinguished by the presence of a Weberian apparatus, a series of bony parts connecting the swim bladder and inner ear. Superficially the Characiformes somewhat resemble their relatives the minnows. One noticeable difference is the presence of a small fleshy adipose fin between the dorsal fin and tail. The presence of teeth within the mouth is also often present as most (though not all species) are carnivorous. However, there are exceptions to both of these. Barbels are always absent and the body is almost always covered in well-defined scales. The mouth is also usually not truly protractile.
[edit] Distribution
Characins are found in tropical lakes and rivers throughout most of South America, Central America, and central Africa. At least 209 species of characins are found in Africa, including the Citharinoids, the Alestiids, and the monotypic Hepsetidae, Hepsetus odoe. The rest of the characins originate from the Americas. This and other evidence suggests they first diversified during the Cretaceous period, though fossils are poorly known.
All extant species are freshwater, though it was probable that certain ancient species were either brackish or marine.
[edit] Relationship to humans
A few characins become quite large, and are important as food or game. Most, however, are small shoaling fish. Many species are popular in aquaria thanks to their bright colors, general hardiness, and tolerance towards other fish in community tanks.
[edit] References
- "Characiformes". FishBase. Ed. Ranier Froese and Daniel Pauly. Feb 2007 version. N.p.: FishBase, 2007.
- Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0471250317
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