It’s o-fish-ial – fish can do MATHS! Stingrays and zebra mbuna can add and subtract just like humans, study reveals
- Zebra mbuna and stingrays can add and subtract one from numbers one to five
- That is the finding of new study carried out by researchers at University of Bonn
- Fish shown cards with either blue shapes for addition or yellow for subtraction
- Zebra mbuna learnt what they meant after 28 sessions and stingrays 68 sessions
Their poor memories mean fish are often seen as the dunces of the animal kingdom.
But a new study suggests that view may be a little misguided because stingrays and zebra mbuna have been found to add and subtract just like humans.
Researchers from the University of Bonn in Germany said their findings highlight that the numerical abilities of fish are on par with those of other vertebrate and invertebrate species.
A new study found that stingrays and zebra mbuna were able to add and subtract. Fish were shown cards with either blue or yellow shapes (pictured), and then presented with two gates containing cards with different numbers of shapes — one of which was the correct answer
Researchers from the University of Bonn in Germany found that Zebra mbuna – a species of cichlid fish – and stingrays (pictured) can add and subtract one from the numbers one to five
HOW INTELLIGENT ARE STINGRAYS?
Stingrays and manta rays have both garnered a reputation for their high levels of intelligence.
There are two scales of how intelligence is roughly estimated in different species, brain mass and brain size relative to the animal’s body.
Manta rays certainly measure up well on the former as they have the largest brain of any fish.
What distinguishes the manta ray, as well as animals like humans and elephants, is that the brain is very large when compared to the body.
This means the animal has invested heavily over the course of its evolution in its brain power, indicating a clear advantage to greater intelligence and concerted effort to improve its capacity.
Stingrays, on the other hand, exhibit more low-key intelligence.
They can manipulate objects to get food and will engage in playful behaviour just for their amusement.
Researchers came to their conclusion after testing whether the creatures could be trained to recognise the colour blue as a symbol for addition and the colour yellow as a symbol for subtraction.
Fish were shown cards with either blue or yellow shapes, and then presented with two gates containing cards with different numbers of shapes — one of which was the correct answer.
For example, if a fish was shown a card with three blue shapes, they would add one to three and swim through a gate containing the card with four shapes.
If a fish swam through the correct gate they were rewarded.
Researchers found that Zebra mbuna – a species of cichlid fish – and stingrays can add and subtract one from the numbers one to five.
Vera Schluessel and her colleagues carried out their research on eight zebra mbuna and eight freshwater stingrays.
The researchers found that six of the zebra mbuna and three of the stingrays learned to consistently associate blue with addition and yellow with subtraction.
On average, zebra mbuna learnt this after 28 sessions and stingrays after 68 sessions.
Fish generally performed well in the tasks, although addition was learned more easily than subtraction and the performance of individual fish varied more between zebra mbuna than between stingrays, the authors said.
‘In conclusion, the ability to “count” and to perform simple arithmetic processes is not just present in humans, non-human primates and birds, but also in invertebrates such as honey bees and spiders and not surprisingly also in fish, both teleosts and elasmobranchs,’ they wrote in their paper.
‘Large intraspecific differences (cichlids) and a considerably high number of unsuccessful individuals (stingrays) indicate that numerical abilities may not be of particular importance to both P. zebra and P. motoro.’
The authors added: ‘Nonetheless, individuals that passed the training stages maintained very high-performance levels.
‘Results confirm previous findings that fish possess many of the same cognitive abilities and to a similar extent as birds and mammals.’
For example, if a fish was shown a card with three blue shapes, they would add one to three and swim through a gate containing the card with four shapes. If fish swam through the correct gate they were rewarded
On average, zebra mbuna (pictured) learnt that blue meant addition and yellow subtraction after 28 training sessions, while it took stingrays 68 sessions
During the addition tasks, zebra mbuna selected the correct answer in 296 out of 381 (78 per cent) tests and stingrays selected the correct answer in 169 out of 180 (94 per cent) tests.
During the subtraction tasks, zebra mbuna were correct during 264 out of 381 (69 per cent) of tests and stingrays were correct in 161 out of 180 (89 per cent) of tests.
Although the researchers think that numerical abilities may not be that important to either species, they believe it could help the creatures recognise individual fish by their appearance, for example by counting stripes or spots on fish bodies.
They added that the findings add to a growing body of evidence indicating that the cognitive abilities and sentience of fish need to be revisited.
The study has been published in the journal Scientific Reports.
WHAT IS THE MIRROR TEST OF ANIMAL INTELLIGENCE?
The mirror test was developed by psychologist Gordon Gallup Jr in 1970 as a method for determining whether a non-human animal has the ability of self-recognition.
It’s also known as the ‘mark test’ or ‘mirror self-recognition test’ (MSR).
When conducting the mirror test, scientists place a visual marking on an animal’s body, usually with scentless paints, dyes, or stickers.
They then observe what happens when the marked animal is placed in front of a mirror.
The researchers compare the animal’s reaction to other times when the animal saw itself in the mirror without any markings on its body.
Animals that pass the mirror test will typically adjust their positions so that they can get a better look at the new mark on their body, and may even touch it or try to remove it.
They usually pay much more attention to the part of their body that bears a new marking.
Even if an animal doesn’t pass the test, they may still have interesting reactions to their reflections.
Many species respond aggressively, or even show affectionate behaviour. In such cases, it might be that the animal mistakes its reflection for another of its kind. This can lead to some amusing sights for human observers.
Humans are able to pass the mirror test when they are around 18 months old. But how do other animals fare?
Currently, a number of animal species have passed the mirror test. Not all individuals of each species pass, but many do.
Animals that have passed the test include:
- Asian Elephants
- The Great Apes
- Bottlenose Dolphins
- Orca Whales
- Eurasian Magpies
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