Zebra mbuna is a fresh water fish. It lives in Lake Malawi in east-central Africa. It is no more than ten centimeters long. They live in colonies organized according to a well-established hierarchy. And if it is harmless to us humans, it does not like, but then absolutely not, that an intruder seeks to breed on its territory.

The stingrayIt lives in the Atlantic and the Mediterranean. It includes the tail, and its length can reach two and fifty meters. It is a solitary fish that loves to hide in the sand. And if you get close to it, it may get frightened and aim the sting at its tail to sting you and inject you with a venom that can be deadly.

Presented as such, these two fish seem to have nothing in common. Although…

Before we go any further, it seems important to clarify that researchers have known for some time that some fish have a sense of numbers. They are not the only ones in this case, in the animal world. Away from this. This ability is present in all classes vertebrates. And even in some invertebrates. Bees for example. They are even able to perform simple calculations.

What if the bees – spiders Also, apparently – find out how to do it, so why not fish? This is the question the researchers asked. And to answer it, they chose to work with… zebra mbuna and stingrays. Because, from their perspective of numbers, it’s surprising that these two things are a lot similar to ours. ShotEye to a small amount of coins on the floor and they immediately know how many coins there are. Probably without actually having to count.

amazing ability

So the researchers wanted to see if they could train these fish in a short math game. Practice addition and subtraction. very simple. Operations that consist of adding or removing only “one” from an initial quantity. It has succeeded!

how ? following the same protocol Of those that were used to show the computational abilities of bees. Researchers introduced Geometric shapes for fishing. with the symbol the color : blue for addition and yellow for subtraction. So when the fish were presented with four blue squares, they had to move to the group of five. That’s four plus one. With, of course, a gourmet bonus at the end of the day.

To make sure the fish didn’t associate the color blue with a larger amount, the researchers presented them with three blue squares with the option to choose between four or five squares. Fish made the right choice. Proof that they have not learned the rule “Choose the largest – or the smallest – quantity”But the rule “Add – or subtract – one”.

The amazing thing is that the fish persisted in its arithmetic power, even when the researchers presented it with objects of various shapes. Understand that the four can be well represented by a small circle, a large circle, a square, and a triangle. prove a working memory Incredibly effective for these little monsters that don’t even have cerebral cortex. This part of brain It participates in complex cognitive tasks in mammals. And who do not need to pre-develop this kind of ability in nature. Further proof that zebra mbuna and stingray… are not that stupid!