Spectral and spatial properties of polarized light reflections from the arms of squid (Loligo pealeii) and cuttlefish (Sepia officinalis L.)

Publication Type:Journal Article
Year of Publication:2007
Authors:T. H. Chiou, Mäthger, L. M., Hanlon, R. T., Cronin, T. W.
Journal:Journal of Experimental Biology
Volume:210
Pagination:3624-3635
Date Published:Oct
Type of Article:Article
ISBN Number:0022-0949
Accession Number:ISI:000251107700017
Keywords:behavior, Cephalopod, Cephalopoda, cuttlefish, iridophore, iridophores, LOLLIGUNCULA-BREVIS, morphology, multilayer, neon tetra, PARACHEIRODON-INNESI, patterns, PHYSIOLOGICAL COLOR-CHANGE, Polarized light, signal, squid, structural color, structures
Abstract:

On every arm of cuttlefish and squid there is a stripe of high-reflectance iridophores that reflects highly polarized light. Since cephalopods possess polarization vision, it has been hypothesized that these polarized stripes could serve an intraspecific communication function. We determined how polarization changes when these boneless arms move. By measuring the spectral and polarizing properties of the reflected light from samples at various angles of tilt and rotation, we found that the actual posture of the arm has little or no effect on partial polarization or the e-vector angle of the reflected light. However, when the illumination angle changed, the partial polarization of the reflected light also changed. The spectral reflections of the signals were also affected by the angle of illumination but not by the orientation of the sample. Electron microscope samples showed that these stripes are composed of several groups of multilayer platelets within the iridophores. The surface normal to each group is oriented at a different angle, which produces essentially constant reflection of polarized light over a range of viewing angles. These results demonstrate that cuttlefish and squid could send out reliable polarization signals to a receiver regardless of arm orientation.

Alternate Journal:J. Exp. Biol.
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