The Optomotor Response in Weak-electric Mormyrid Fish: Can they See?


American Museum of Natural History, Dept. Ichthyology, Central Park West at 79th St., New York, N. Y. 10024, U.S.A.

C.N.R.S.-L.P.N. 3, F-91190 Gif-sur-Yvette, France.


The present study has explored the optomotor response in two species of mormyrid fish, Gnathonemus petersii and Brienomyrus niger. Both species tended to follow a black and white striped stimulus pattern under illumination levels of 6, 12, and 60 lx. The optomotor response ceased to occur under 540 lx. The behavioral data support earlier histological findings implicating the mormyrid retina in dim light vision.