The genus Polypterus, common name bichir, is a basal representative of the actinopterygian (ray-finned) fishes. It is a member of the Cladistia, a group possessing lungs, heavy ganoid scales (external layer of ganoine), lobe-like pectoral appendages, two gular plates (visible in the Roll movie, particularly in the isolated head), external gills as young, a spiral valve in the intestine and a diphycercal tail. This odd assemblage of primitive characters (shared with an assortment of pre-amniote gnathostomes) is contrasted with a number of uniquely derived characters, including dorsal "flagfins," a series of 8-15 dorsal fins each with a leading edge spine to which are attached horizonal fin rays.

All living members of the Cladistia are in the family Polypteridae, with nine species and two genera, and are confined to the freshwaters of tropical or subtropical Africa. The genus Polypterus contains eight of the nine species. They are most easily recognized by the dorsal "flagfins". Each of the 8-15 dorsal fins has a leading edge spine to which are attached horizonal fin rays. Bichirs are bimodal in respiratory function--they have both gills and well vascularized lungs--and can survive using either.

Click on the image above to see a movie illustrating the paired lungs of the bichir.

This specimen was collected 4 May, 1970 in the state of Kwome, Ghana, Africa. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. William Fink of the University of Michigan. The specimen had been partially dissected in the region of the left pectoral fin. Funding for scanning and image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

Lateral view of the 140 mm standard length scanned specimen.

This specimen was scanned by Richard Ketcham on 3 February 2003 along the coronal axis for a total of 1531 1024x1024 pixel slices. Each slice is 0.095 mm thick, with an interslice spacing of 0.095 mm and a field of reconstruction of 28.0 mm.

Gosse, J.-P., 1990. Polypteridae.. p. 79-87. In C. Lévêque, D. Paugy and G.G. Teugels (eds.) Faune des poissons d'eaux douces et saumâtres d'Afrique de l'Ouest. Tome I. Coll. Faune Tropicale n° XXVIII. Musée Royal de l'Afrique Centrale, Tervuren and O.R.S.T.O.M., Paris, 384 p.

Links

Fishbase

NCBI Taxonomy Browser (sequence links)

Tropical fish information

None available.