Researchers have discovered that triggerfish, a species of fish that lives in coral reefs, are capable of seeing colors that humans can’t detect. The findings suggest that reef fish see a different range of colors due to the complexity of their environment. The details are in a new paper that was published in the journal Royal Society Open Science.
The lagoon triggerfish (Rhinecanthus aculeatus) is a predatory marine fish found in coral reefs throughout the Indo-Pacific. While previous studies have investigated the color vision of freshwater fish, including goldfish and zebrafish, there had been little research on reef fish. Triggerfish have both single cones and double cones in their eyes but their ability to discriminate colors had yet to be fully explored.
A research team from The University of Queensland trained triggerfish to respond to specific reward colors. When given the choice between two colored panels, the fish were trained to poke the correct color and were rewarded with a food paste. The researchers gave the fish progressively similar colors to test their color discrimination abilities.
The triggerfish had excellent color discrimination skills and were able to see certain colors in more detail than humans. The fish were especially adept at detecting differences in shades of blue, suggesting that their environment had shaped this adaptation. The researchers note that reef fish live in colorful, complex environments and would benefit from having good color discrimination.
For the first time, a study has shown that reef fish can see colors that aren’t visible to humans. Lagoon triggerfish performed well in color discrimination tasks, especially when compared to freshwater fish such as goldfish. The findings will help researchers understand how marine animals see their world, especially as reef colors shift due to coral bleaching events. Comparative color vision research has other applications, too, including improving computerized color detection.
M. Champ, M. Vorobyev, and N. J. Marshall. Colour thresholds in a coral reef fish. Royal Society Open Science (2016).