For humans, counting is as easy as 1-2-3. But for animals? Evidence is mounting that other primates, and even birds and fish, can discriminate between quantities differing by only one item, at least up to a quantity of five. Cichlids and stingrays are also able to distinguish between quantities differing by just one item, a new study published today (March 31) in Scientific Reports suggests.
“Some research has been done on the numerical abilities of bony fish, but nothing was known for sharks and stingrays,” says Vera Schluessel, a cognition researcher at the University of Bonn in Germany. So she and her co-authors trained eight freshwater stingrays (Potamotrygon motoro) to associate colors with relative amounts. The team also trained eight bony fish (Pseudotropheus zebra cichlids) to serve as a comparison.
All of the fish were taught to recognize blue as corresponding to “more” and yellow to “less.” The fish or ...
