Count on Them: Sting Rays And Zebra Mbuna Can Add And Subtract Small Numbers

Recent studies have shown that salamanders, bees, and bird brains all have simple arithmetic abilities. The small but growing list of animals that can do basic addition and subtraction has been expanded by a new study.

This ability was demonstrated by the freshwater stingrays and zebras.

Individuals did not just learn to pick the highest or lowest number presented based on the respective color, but they had to learn to add or subtract.

Fishes were shown two gates with different numbers of cards. They were trained that if they were shown a card with three blue squares, the door with the reward behind it would be the one with four blue squares. If the card shapes were yellow, they would have to subtract one from the number of shapes to identify the door.

Not all individuals succeeded in learning the task, but those that did did a good job. The Stingrays chose the correct door 94 percent of the time for addition and 89 percent of the time for subtraction.

Both species found it easier to learn addition than it was to learn subtraction.

The team notes that the fish were quicker at understanding their task, and more of them were successful.

The two completely different groups of fishes seem to have the ability to perform basic arithmetic despite not having any known ecological or behavioral need for it.

Both species are opportunist feeders, not hunters, and do not seem to prefer particular-sized social groups.

This ability could be critical for distinguishing individuals by their physical characteristics.

The team posed a question as to why animals such as fish are referred to as "primitive" or "lower".

The fishes are on a small list of animals with confirmed capabilities of adding and subtracting outside of birds and mammals. We have yet to test more clever creatures.

The researchers concluded that fish have the same cognitive abilities as birds and mammals.

While we have come a long way from believing animals are thoughtless biological machines driven solely by instinct, we still only just started working out how intelligent our fellow living beings really are.

Our unprecedented cognitive abilities did not just arise miraculously, they developed within species that preceded us from seeds planted in our ancient evolutionary history, shared by many other animals on our planet.

Scientific Reports published this research.