Osteichthyes

Osteichthyes or bony fish (from Greek osteon, bone, and ichthys, fish) are a taxonomic group of fish that includes the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The group is characterised by having a skeleton primarily composed of bone tissue, as opposed to cartilage. The vast majority of fish are members of Osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, and over 435 families and 28,000 species.

Characteristics

Osteichthyes are characterised by a skeleton made of bone. Their fins contain hard rays or spines because they are stiffened with bone. The remainder of the body is covered in scales which are often covered in a layer of mucus that can help the fish glide through water.

Classification

Osteichthyes are divided into two classes, the Actinopterygii, or ray-finned fish, and the Sarcopterygii, or lobe-finned fish. The Actinopterygii include the familiar fish of most fishery catches, such as cod, bass, and tuna. The Sarcopterygii include the coelacanths and lungfishes, although the former are thought to be more closely related to the tetrapods than to the lungfish.

Evolution

The earliest known fossil of a bony fish comes from the Upper Silurian of China (c. 423 million years ago), where the Andreolepis and the Guiyu oneiros were found. They are the oldest known bony fish in the world.

See also

• Fish
• Cartilaginous fish
• Fish anatomy
• Fish scale
• Fish development

External links

• FishBase, a comprehensive database of fish species

Osteichthyes Resources
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