Cottus cognatus: Master of Disguise.

Abstract

Cryptic coloration is an antipredatory defense mechanism in the slimy sculpin that allows them to effectively avoid predation. We assessed the rate of color change in slimy sculpin from dark-to-light substrate and light-to-dark substrate. The relationship between rate of color change and fish length was examined. The rate of color change in the presence of a predator was also tested. We hypothesized that: the rate of cryptic color change between dark-to-light and light-to-dark will be different, there is a relationship between rate of color change and fish length, and the rate of color change would increase in the presence of a predator. The variables measured were time to change color across color change categories from dark-to-light and light-to-dark, rate of color change of sculpin across fish length, and time to change color across color change categories from dark-to-light in the absence and presence of a predator. We found that rate of color change was different from dark-to-light and light-to-dark. Our data suggested that there is a relationship between time to change color and fish length for dark-to-light (increasing) and light-to-dark (decreasing). We also found that the predator did not affect rate of color change but affected extent of color change. Changes in cryptic coloration in different environments depend on factors such as predatory recognition and assessment, intraspecific interference competition, and chromatophore plasticity which play key roles in the success of a fish's survival.