THE OCEAN DEEP

Polypterus is a genus of freshwater fish in the bichir family (family Polypteridae) of order Polypteriformes. The type species is the Nile bichir (P. bichir). Fishes in this genus live in various areas in Africa (as the species' common names would indicate). The etymology of the genus name derives from a combination of the Greek prefix poly- (many) and the root word pteron (wing or fin) – "many fins." The bichirs are a family, Polypteridae, of archaic-looking ray-finned fishes, the sole family in the order Polypteriformes. All species occur in freshwater habitats in tropical Africa and the Nile River system, mainly swampy, shallow floodplains and estuaries.
Anatomy and appearance
Bichirs are elongated fishes with a distinctive series of up to fifteen dorsal finlets, instead of a single dorsal fin. Each of these finlets have a sharp spine. The body is covered in thick, bonelike, ganoid scales. Their jaw structure more closely resembles that of the tetrapods than that of the teleost fishes. Bichirs have a number of other primitive characteristics, including fleshy pectoral fins superficially similar to those of lobe-finned fishes. They also have spiracles.
Bichirs have rudimentary lungs, which allow them to obtain oxygen from the air when in poorly oxygenated waters, by swimming quickly to the surface and back to the bottom. They are nocturnal, and feed on small vertebrates, crustaceans, and insects.
Bichirs have a maximum body length of 97 centimetres (3.2 ft), although many species do not exceed 35 centimetres (1.1 ft).
Relationship to humans
Bichirs are popular subjects of public and large hobby aquaria. Though predatory, they are otherwise peaceful and relatively nonactive, preferring to lie on the bottom, and make good tankmates with other species that are large enough not to be prey. Some aquarists note that Loricariid catfish may attack bichirs and suck on their skin.
Species
There are twelve extant species in two genera:
Order Polypteriformes
• Family Polypteridae
o Genus Erpetoichthys
• Reedfish, Erpetoichthys calabaricus Smith, 1865.
o Genus Polypterus
Polypterus ornatipinnis
• Guinean bichir, Polypterus ansorgii Boulenger, 1910.
• Polypterus bichir
• Nile bichir, Polypterus bichir bichir Lacépède, 1803.
• Polypterus bichir katangae Poll, 1941.
• Polypterus bichir lapradei Steindachner, 1869.
• Barred bichir, Polypterus delhezi Boulenger, 1899.
• Polypterus enlicheri
• Polypterus endlicheri congicus Boulenger, 1898.
• Saddled bichir, Polypterus endlicheri endlicheri Heckel, 1847.
• Polypterus mokelembembe Schliewen & Schafer, 2006.
• Ornate bichir, Polypterus ornatipinnis Boulenger, 1902.
• Polypterus palmas
• Polypterus palmas buettikoferi Steindachner, 1891.
• Shortfin bichir, Polypterus palmas palmas Ayres, 1850.
• Polypterus palmas polli Gosse, 1988.
• West African bichir, Polypterus retropinnis Vaillant, 1899.
• Polypterus senegalus
• Polypterus senegalus meridionalis Poll, 1941.
• Gray bichir, Polypterus senegalus senegalus Cuvier, 1829.
• Polypterus teugelsi Britz, 2004.
• Mottled bichir, Polypterus weeksii Boulenger, 1898.
Extinct species include:
• Polypterus faraou Otero et al., 2006 — late Miocene.