Polypterus
| Polypterus | |
|---|---|
 |
|
| Polypterus delhezi | |
 |
|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Subclass: | Cladistia |
| Order: | Polypteriformes |
| Family: | Polypteridae |
| Genus: |
Polypterus Lacépède, 1803 |
| Species | |
|
see text |
|
see text
Polypterus is a genus of freshwater fish in the bichir family (Polypteridae) of order Polypteriformes. The type species is the Nile bichir (P. bichir). Fishes in this genus live in various areas in Africa. The etymology of the genus name derives from a combination of the Greek prefix πολυ-, poly- (many) and the root word πτερον, pteron (wing or fin) – "many fins". Polypterus is the only known vertebrate to have lungs, but no trachea.
In shallow water, Polypteris inhales primarily through its spiracle (blowhole). Exhalation is powered by muscles in the torso. During exhalation, the bony scales in the upper chest become indented. When the muscles are relaxed, the bony scales spring back into position, generating negative pressure within the torso, resulting in a rapid intake of air through the spiracle. The air is nearly sufficient to fill the lungs. This is followed by one cycle of buccal (mouth) pumping, which "tops off" the lungs, with the surplus air from the buccal pumping process discharged through the pharynx. According to one hypothesis, Devonian tetrapods may have inhaled in this way.
Polypterus was discovered, described, and named in 1802 by Étienne Geoffroy Saint-Hilaire. It is a genus of 10 green to yellow-brown species. Naturalists were unsure whether to regard it as a fish or an amphibian. If it were a fish, what type was it: bony, cartilaginous, or lungfish?
Some regarded Polypterus as a living fossil, part of the missing link between fishes and amphibians, helping to show how fish fins had evolved to become paired limbs.
...
Wikipedia