Video analyses of chromatophore activity in the European cuttlefish, Sepia officinalis

There is a paucity of quantitative methods to measure chromatophore activity in cephalopods, without which, important questions regarding chromatophore function cannot be addressed. These questions include the mechanisms underlying graduated responses by chromatophores and the variations in responses by chromatophore color type. We have developed an efficient and accurate method to record and analyze the activity of individual chromatophores using a combination of video capture and computer analysis techniques. High performance video recordings were obtained from 20 to 40 chromatophores isolated from the fin of the European cuttlefish, Sepia officinalis. Captured frames were imported into MATLAB for image segmentation analyses using polygon masking to identify individual chromatophores. RGB thresholds were determined for each chromatophore analyzed and were used to follow the activity of individual chromatophores and to discriminate yellow and red-black chromatophores. Data from tests using colored paper squares and live chromatophores confirmed the utility of this novel procedure.