Osteichthyes: Difference between revisions
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The vast majority of fish are osteichthyes. Osteichthyes are an extremely diverse and abundant group consisting of over 29,000 species, making them the largest class of vertebrates in existence today. |
The vast majority of fish are osteichthyes. Osteichthyes are an extremely diverse and abundant group consisting of over 29,000 species, making them the largest class of vertebrates in existence today. |
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a fish that has scales, skeletone, and fins. |
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== Characteristics == |
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Osteichthyans are characterized by a relatively stable pattern of [[cranial bone]]s, rooted, medial insertion of [[Mandible|mandibular]] muscle in lower jaw. The head and [[pectoral girdle]]s are covered with large dermal bones. The eyeball is supported by a [[sclerotic ring]] of four small bones, but this characteristic has been lost or modified in many modern species. The labyrinth in the [[inner ear]] contains large [[otolith]]s. The braincase, or neurocranium, is frequently divided into [[anterior]] and [[posterior]] sections divided by a [[fissure]]. |
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Bony fish typically have [[swim bladder]]s, which helps the body create a neutral balance between sinking and floating. However, these are absent in many species, and have developed into primitive lungs in the lungfishes. They do not have fin spines, but instead support the fin with [[lepidotrichia]] (bone fin rays). They also have an [[Operculum (fish)|operculum]], which helps them breathe without having to swim. |
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They also are able to see in color, unlike most other fish.{{fact|date=January 2009}} |
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Bony fish have no [[placoid scales]]. Mucous glands coat the body. Most have scales of sort: ganoid, cycloid, or cytenoid. These scales are smooth and overlapping. |
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===Skeleton=== |
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The skeleton is made of bone and cartilage, and is almost completely calcified. The vertebral column, cranium, jaw, ribs, and intramuscular bones make up the skeleton. |
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One of the best-known innovations of the osteichthyans is [[endochondral ossification|endochondral bone]] or "replacement" bone, which is bone ossified internally, by replacement of [[cartilage]], as well as perichondrally, as "spongy bone." In vertebrates, in general, there are various types of calcified tissue: [[dentine]], [[tooth enamel|enamel]] (or "enameloids") and [[bone]], plus variants characterized by their ontogeny, chemistry, form and location. Endochondral bone is unique because it begins life as cartilage. |
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In lower vertebrates, cartilaginous structures can become superficially calcified. However, in osteichthyans, the circulatory system invades the cartilaginous matrix. |
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This fish is not known in all areas of the ocean, but can be found in lakes or rivers. |
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==Biology== |
==Biology== |
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Revision as of 22:28, 29 May 2009
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| Atlantic herring | |
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| Superclass: | Osteichthyes* Huxley, 1880
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Osteichthyes (Template:Pron-en), also called bony fish, are a taxonomic group of fish that includes the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The split between these two classes occurred about 450 million years ago.[1]
In most classification systems[2] the Osteichthyes are paraphyletic with land vertebrates. That means that the nearest common ancestor of all Osteichthyes includes tetrapods amongst its descendants. Actinopterygii (ray-finned fish) are monophyletic, but the inclusion of Sarcopterygii in Osteichthyes causes Osteichthyes to be paraphyletic.
Most bony fish belong to the ray-finned fish (Actinopterygii); there are only eight living species of lobe-finned fish (Sarcopterygii), including the lungfish and coelacanths.
They are traditionally treated as a class of vertebrates, with subclasses Actinopterygii and Sarcopterygii, but some newer schemes divide them into several separate classes.
The vast majority of fish are osteichthyes. Osteichthyes are an extremely diverse and abundant group consisting of over 29,000 species, making them the largest class of vertebrates in existence today.
a fish that has scales, skeletone, and fins.
Biology
Most bony fish breathe through gills.
Lungfish and other osteichthyan species, are capable of respiration through lungs or vascularized swim bladders. Other species can respire through their skin, intestines, and/or stomach[3].
Osteichthyes are ectothermic (cold blooded), meaning that their body temperature is dependent on that of the water. They can be any type of heterotroph: omnivore, carnivore, herbivore, or detrivore.
Some bony fish are hermaphrodites. Fertilization is usually external, but can be internal. Development is usually oviparous (egg-laying) but can be ovoviviparous, or viviparous. Although there is usually no parental care after birth, before birth parents may scatter, hide, guard or brood eggs.
Examples
The ocean sunfish is the largest bony fish in the world, while the longest is oarfish. Specimens of ocean sunfish have been observed up to 3.3 metres (11 ft) in length and weighing up to 2,300 kilograms (5,100 lb). Other very large bony fish include the Atlantic blue marlin, some specimens of which have been recorded as in excess of 820 kilograms (1,810 lb), the black marlin, some sturgeon species, the giant grouper and the goliath grouper, both which can exceed 400 kilograms (880 lb) in weight. In contrast, the dwarf pygmy goby measures a minute 15 millimetres (0.59 in).
Arapaima gigas is the largest species of freshwater bony fish. The largest bony fish ever was Leedsichthys.
See also
- Ostracoderm - armoured jawless fishes.
- Acanthodians - relatives of the bony fishes
References
 | This article needs additional citations for verification. (January 2009) |
- ^ Dawkins, Richard. The Ancestor's Tale. ISBN 0297825038.
- ^ A Tree of Life
- ^ Helfman G.S., B.B. Collette and D.E. Facey. The Diversity of Fishes. Blackwell Sciences, 1997