Clown fish has the ability to count!
In a new study, researchers found that clownfish can count.
Nemo may have been the innocent, calm little fish most of us know in the classic cartoon, but a new study shows that real clownfish are more boisterous, aggressive, and more importantly, they can count!
According to ISNA, citing SF, Japanese researchers say that these species use counting to distinguish between friends and enemies and check the stripes on the bodies of invaders and co-habitants who enter their ocean homes.
Scientists observed the reaction of these orange fish to equal or similar species of fish with one to three white stripes. They found that clownfish count the lines on the body of other fish and show a greater aversion to fish that have three lines like themselves, and also to some extent to two-line fish. However, they generally ignored fish that had a line or no line.
The study, conducted by Kina Hayashi of the Okinawa Institute of Science and Technology and her team, demonstrates the clownfish's impressive eye-counting ability.
Contrary to Pixar's portrayal of Nemo and his peers as timid, friendly species, real clownfish fiercely defend their anemone homes against intruders. While they live peacefully with some species, they often find coexistence with their own species undesirable.
Clownfish species that share the same habitat show different stripe patterns, from three vertical white stripes to no stripes at all. Previous research has shown that coral reef fish, including clownfish, develop bands to be recognized among the population. However, the researchers' goal was to understand how anemones distinguish between their own species and those of other species.
Dr. Hayashi and his colleagues raised a group of clownfish and made sure they were never exposed to other species of clownfish. At six months of age, the researchers recorded the juvenile clownfish's reactions to different species, including Clark's clownfish, orange skunk clownfish, saddleback clownfish, as well as their own species. Common clownfish showed the most aggression compared to their own species with three white stripes, and conflicts occurred up to 80% of the time.
Other species met with less hostility. The orange skunk clownfish had the fewest encounters. Meanwhile, Clark's and Zini's clownfish experienced light encounters with two and three white lines, respectively.
Dr. Hayashi says: Common clownfish attack more of their own kind.
Despite observing frequent attacks on their own species, researchers wondered how clownfish distinguish between themselves and others. In further experiments, they exposed small groups of juvenile clownfish to patterns with varying numbers of white stripes. This fish did not show much interest in a simple orange model, and they occasionally encountered single-striped fish, but they were more aggressive than three-way models, which shows their dislike of sharing space with similar fish. The two-line model was also met with unpleasant reception.
Dr. Hayashi says that the aversion to double-lined fish may be related to their development, because common clownfish initially have two lines, and then another white line is added. This suggests that the clownfish may also see the double-lined fish as a competitor.
