Researchers from the University of Rhode Island have demonstrated that some cichlids do not need to use their eyes to feed.
Jacqueline Webb and her colleagues have demonstrated that cichlids in the genus Aulonocara feed by using their lateral line sensory system to detect minute vibrations made by prey hidden in the sediments.
The scientists tested the hypothesis that the lateral line system mediates prey detection in Aulonocara by tethering brine shrimp in petri dishes randomly placed in the sandy substrate of an experimental tank and using digital video to describe prey detection behaviour of individual fishes.
According to Webb, Aulonocara species have widened lateral line canals that are highly sensitive to vibrations and water flows. They feed by gliding through the water with their chin close to the sand like a metal detector, seeking out twitching arthropods and other unseen prey items.
These cichlids join a short list of fish that have been demonstrated to use their lateral line system to feed, said Webb. Since most of the fish with widened lateral line canals are found in the deep sea, it's difficult to study them. These cichlids can now be used as a model system for studying widened canals, and we can apply what we learn from them to the fish in the deep sea.
We also hope that this work will allow us to determine whether the sensory biology of a species can be used to predict its ecological success, continued Webb, especially in environments where the water quality is poor or where there is increased turbidity. Do these fish have an advantage in water where it is difficult to see well?