Bichirs: Polypteriformes

Bichirs (bi-CHURS) have a slender body that is 16–47 inches (40–120 centimeters) long. The dorsal (DOOR-suhl) fin, the one that runs along the top, is divided into a series of small spiny fins, called finlets. Bichirs have a tubular pair of nostrils that extends in front of the mouth, and they have many small, sharp teeth. These fishes have a dense covering of shiny, diamond-shaped scales arranged in diagonals. On the inside, bichirs have paired swim bladders that function as air-breathing organs. This feature is unusual, because fishes usually use the swim bladder to control their position in the water. The right swim bladder is larger than the left one. Bichirs are olive brown to dark brown on the top and sides and over the head but are creamy white on the bottom. Some have dark or clear spots and blotches and irregular stripes, but others are a solid color. The heads of most bichirs are spotted.