MORMYRID

also called Mormyr, any of several species of slimy freshwater African fishes that comprise the family Mormyridae (order Mormyriformes). They are usually found in sluggish, muddy water. Mormyrids are soft-rayed bony fishes with abdominal pelvic fins, forked tail fins, small mouths and eyes, restricted gill openings, and small scales. They range from 9 to 50 cm (3.5 to about 20 inches) in length. Their brains are proportionately very large, comparable to that of humans in relation to body weight; enlarged areas of the brain indicate well-developed senses. A loosely attached bony plate on each side of the head covers a vesicle that communicates with the internal ear. Paired electric organs of mild power, present in the tail, set up a continuous electric field around the fish, acting as a sensory screen. Most mormyrids feed on small prey, aquatic vegetation, or organic debris. More than 100 species of unusual appearance are placed in about 11 genera. The elephant-snout fishes, species of Gnathonemus, have the mouth at the end of a long, trunklike snout. Other mormyrids have narrow heads, protruding lower lips, or short, rounded snouts. The Nile species of Mormyrus are represented in ancient Egyptian mural paintings and hieroglyphics.