Freshwater stingrays make mental maps


New research has shown that freshwater stingrays make spatial maps to help them find their way around.

Schluessel and Bleckmann, researchers at the University of Bonn in Germany, kept young Amazonian river stingrays, Potamotrygon motoro, in special experimental aquariums which were fitted with a maze to test the navigational skills of the fish.

Their findings, which have just been reported in the Journal of Comparative Physiology, Neuroethology, Sensory and Behavioural Physiology, show that the stingrays were able to solve spatial tasks by constructing cognitive maps of their environment.

To test the navigational skills of the rays, the pair set up two different experiments for the fish - allocentric and ego-allocentric, both of which involved the rays having to find food hidden with a four-armed maze.

In each test, the food was placed in the same position in the maze, but the starting position for the fish in one of the tests varied, while in the other test the fish were always introduced in the same spot.

The fish in both groups were all able to solve the tests, but they appeared to use different orientation strategies within the maze.

Bleckmann and Schluessel conclude: \"Allocentrically trained rays reached the goal via novel routes starting from unfamiliar locations, while ego-allocentrically trained rays primarily solved the task on the basis of an egocentric turn response.

\"Our data suggest that P. motoro orients by constructing a visual cognitive map of its environment, but also uses egocentric and/or other orientation strategies alone or in combination for spatial orientation, a choice which may be governed by the complexity of the problem. We conclude that spatial memory functions are a general feature of the vertebrate brain.\"

For more information see the paper:

Schluessel V, Bleckmann H. (2005) - Spatial memory and orientation strategies in the elasmobranch Potamotrygon motoro. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2005 May 14;