Macroscale and Microscale Structural Characterization of Cephalopod Chromatophores

Report No. ARL-RP-0318
Authors: Keith M. Kirkwood, Eric D. Wetzel, George Bell, Alan M. Kuzirian, and Roger T. Hanlon
Date/Pages: April 2011; 14 pages
Abstract: Cephalopods, the class of mollusks that include squid, cuttlefish, and octopus, possess skin with dynamic adaptable appearance. Their unique ability to rapidly change their visual appearance is enabled in part by a layer of skin containing thousands of chromatophore organs. These organs consist of a pigment sac connected to 15-25 radially arranged muscles. Muscle contraction and relaxation controls the expansion state of the sac, which alters the size of its presented area and the skin color. This study examines the chromatophore organs in detail, to investigate the global and local structure and characterize mechanical properties of skin from the squid Loligo pealeii. A biaxial membrane inflation test and digital image correlation was used to measure the biaxial modulus, strain limits, plus strain and damage fields on the skin during bulge experiments. Microscopy was used to examine chromatophore substructures and determine their connectivity and functional relationships with surrounding structures.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2011