Researchers at the Okinawa Institute of Science and Technology have discovered that clownfish have counting skills. They are able to accurately determine the number and size of white stripes on each other’s bodies – but use this skill only to defend territory. Woe to the individual whose stripes coincide with those of the “owner” of a particular house-actinia – it will be mercilessly expelled.
The formation of white stripes in clownfish is considered one of the main signs of maturation. Three wide and brightly coloured stripes on the body is a sign of an adult. As a rule, by this time it has its own home in the form of a separate actinia (coral polyp). This is a successful, but fragile symbiosis, so the fish is not going to allow anyone to go there – especially its closest relatives.
In the course of research, scientists have found that the older the individual, the more ruthless she is to all other clownfish. The alpha female always drives out all the newcomers, but even if we are talking about a colony of young fish, there too the largest female takes on the function of “guard”. To avoid confusion, clownfish recognise each other’s age and status by the type and number of white stripes on their bodies.
