Cuttlefish adjust body pattern intensity with respect to substrate intensity to aid camouflage, but do not camouflage in extremely low light

Abstract Cuttlefish are able to camouflage to a wide variety of natural backgrounds that contain varying colors, intensities and patterns. Numerous studies have investigated the visual cues that influence cuttlefish body pattern expression, yet none have addressed experimentally how well overall intensity is matched between animal and substrate. Here, cuttlefish were tested on artificial and natural substrates that varied in intensity and were illuminated by different light levels; calibrated grayscale photographs were used to analyze the intensity of cuttlefish and their surrounding substrates. We found that cuttlefish scaled their body pattern intensity with respect to substrate intensity under bright and moderate lighting conditions, but not under low or extremely low lighting conditions. Surprisingly, in extremely low light (