© 2004 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
Discrete model of fish scale incremental pattern: a formalization of the 2D anisotropic structure
a SES, Inc. and World Data Center for Oceanography, Silver Spring; Ocean Climate Laboratory NODC/NOAA, E/OC5, 1315 East West Highway, Room 4308, Silver Spring, MD 20910-3282, USA
b Hard Tissue Research Unit, Department of Biomaterials and Biomimetics, New York University College of Dentistry 345 East 24th Street, New York, NY 10010, USA
*Correspondence to I. Smolyar: tel: +1 301 713 3290 ext 188; fax: +1 301 713 3303. e-mail: ismolyar{at}nodc.noaa.gov; tim.bromage{at}nyu.edu.
The structure of growth patterns on fish scales is characteristically anisotropic: the number of circuli and their widths significantly vary with the direction of measurement. We show, however, that because of anisotropy, fish scale growth rate variability can be described in fuzzy terms. The index of structural anisotropy is introduced, which serves as a measure of the fuzziness of growth-rate quantification. A discrete model of fish scale incremental pattern is proposed, which takes into account the incremental structure in 2D. This model is based on a representation of the fish scale pattern as a relay network, taking anisotropy in the form of discontinuities and convergences of incremental structural elements into account, and the widths of growth increments in different directions. The model is used to formalize procedures necessary for the quantification of fish scale growth rate. The capability of the model for analysing objects with similar structural attributes as found in fish scale incremental patterns, such as those found in coral, otoliths, shells, and bones, is demonstrated.
Keywords: boolean function, discrete model, fish scale, fuzziness, graph, growth rate, incremental pattern, index of anisotropy, relay network, structure
Received 21 July 2003; accepted 8 July 2004.