(ORDO NEWS) — Experiments with cichlids and rays have shown that fish are good at adding and subtracting small numbers.
Basic arithmetic does not require a brain comparable to that of a human. The ability to add and subtract small numbers is demonstrated by many animals, not only mammals, but also, say, bees.
And a new study by German zoologists has shown that these operations on forces and some fish – at least, rays and cichlids, with which scientists experimented.
Vera Schluessel and her colleagues at the University of Bonn have experimented with the freshwater stingray Potamotrygon motoro and the pseudotropheus cichlid Maylandia zebra.
The fish were placed in front of a pair of gates, which were depicted with several simple geometric shapes in different colors, teaching them to choose one of them in order to receive a tasty reward.
The correct choice depended on the symbols on the card, which was shown to the animals before meeting with the gate.
For example, if a card with three blue squares was shown, then the reward could be found by moving along the path marked with four (three plus one) blue squares. The yellow color corresponded to the subtraction.
Not all fish coped with these “school” tasks. However, six of the eight cichlids and three of the eight rays that participated in the experiments easily figured out what was wrong.
In particular, such “smart” skates made the right choice in 94 addition attempts and 89 percent of subtraction attempts.
It is curious that cichlids also showed relatively better abilities for addition: this operation required fewer training attempts from fish and brought the correct result more often than subtraction.
The fact that cichlids performed better than stingrays may be due to the fact that these specimens have long lived in the laboratory and are constantly used to study behavior and thinking, so they could be better prepared for such tests.
In principle, neither one nor the other species is predatory or highly social, and why they have such abilities in mathematics is unclear.
“A more interesting question is why animals such as fish are still usually described as “primitive” or “lower” vertebrates, write the authors of the work.
“It’s becoming clear that fish, their cognitive abilities, their status and ‘intelligence’ need to be revisited… Many of the cognitive skills that fish exhibit are as good as those of birds and mammals.”
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