Counting Nemo

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In the animal kingdom, counting skills usually help creatures in going after larger meals or finding safety in groups.

But a new study on clownfish showed that the colorful marine species is able to “count” to identify other fish, Science Magazine reported.

The vibrant-looking fish, made famous by the Disney movie, “Finding Nemo,” sports a variety of colors and bright white stripes.

And they are extremely territorial: A clownfish would go so far as to attack and bite other clownfish – or different fish for that matter – invading their homes.

Marine ecologist Kina Hayashi suspected that this aggressive behavior might be related to the number of stripes that the fish use to tell each other apart.

In one experiment, Hayashi and her team placed 50 lab-raised common clownfish in individual tanks. They then added other clownfish species with different stripe patterns.

All the fish were protected inside a smell-proof, transparent box.

Despite being unable to physically confront the intruders due to barriers, the resident clownfish exhibited aggressive behaviors such as rushing the other fish or staring.

The researchers then conducted another experiment with 120 clownfish grouped in threes, which were introduced to decoy fish with varying stripe patterns.

The findings revealed a clear preference for certain stripe configurations among the clownfish. Specifically, they aggressively targeted decoys with three stripes, displaying significantly more aggression compared with those with fewer or no stripes.

This suggests that the number and configuration of stripes play a significant role in triggering aggressive behaviors in common clownfish.

While the study sheds light on how the marine creatures tell each other apart, other researchers questioned whether this means the fish are really counting or just noticing odd colors.

In the future, Hayashi hopes to discover whether this counting ability comes from birth or is a learned skill.

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