Individual Identification of Decapod Crustaceans I: Color Patterns in Rock Shrimp (Rhynchocinetes Typus)

We examined whether color patterns of a marine crustacean may serve to distinguish between individuals and to successfully identify individuals after one molt. Digital images of the rock shrimp Rhynchocinetes typus were digitally processed in order to obtain their diffraction pattern by means of Fast Fourier Transformation (FFT). All diffraction patterns were correlated with a phase-only filter using images of rock shrimp before and after one molt. To determine the degree of similarity of color patterns among rock shrimps, correlation of diffraction pattern was performed. This approach showed that among shrimps the color pattern of the cephalothorax is mainly homogenous (;83%) in both distribution and intensity. However, the observed degree of variability (;17%) was sufficient to distinguish between individuals. Furthermore the general color pattern of each individual persisted after one molt and all 14 individuals could be recognized based on their color pattern. It is concluded that this non-intrusive method for distinguishing among shrimp individuals may be a useful tool that could be developed and used in the future instead of expensive and intrusive tagging techniques.