Slimy sculpins, Cottus cognatus, hidden members of the stream underworld.

Abstract

Slimy sculpin (Cottus cognatus) are equipped with a battery of defense options which include concealment in the substrate, cryptic coloration, cryptic movement and darting. Sculpins live in close proximity to predators which puts a premium on their capacity to cryptically change color and blend into their surroundings. The main objective of the experiment was to examine the rate of color change for sculpins from dark to light and light to dark substrate with and without a predator. Three hypotheses were generated: the rate of change from dark to light (DTL) would be different from light to dark (LTD), small sculpins would change faster than large sculpins and the predator would elicit a faster rate of color change. The rate of change from dark to light and light to dark were different; small sculpins changed faster to the light and large sculpins changed faster to the dark. The predator did not influence the rate of change, but did cause larger fish to go farther to the light extreme.