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Differential coloration patterns in the intertidal crab Neohelice (=Chasmagnathus) granulata

Published online by Cambridge University Press:  23 December 2010

Agustina Méndez Casariego*
Affiliation:
Departamento de Biología (FCEyN), Universidad Nacional de Mar del Plata, CC 573 Correo Central, B7600WAG, Mar del Plata, Argentina Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, CP C1033AAJ, Ciudad de Buenos Aires, Argentina
Tomás Luppi
Affiliation:
Departamento de Biología (FCEyN), Universidad Nacional de Mar del Plata, CC 573 Correo Central, B7600WAG, Mar del Plata, Argentina Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, CP C1033AAJ, Ciudad de Buenos Aires, Argentina
Oscar Iribarne
Affiliation:
Departamento de Biología (FCEyN), Universidad Nacional de Mar del Plata, CC 573 Correo Central, B7600WAG, Mar del Plata, Argentina Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, CP C1033AAJ, Ciudad de Buenos Aires, Argentina
*
Correspondence should be addressed to: A.M. Casariego, Departamento de Biología (FCEyN), Universidad Nacional de Mar del Plata, CC 573 Correo Central, B7600WAG, Mar del Plata, Argentina email: mendezc@mdp.edu.ar
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Abstract

Many crustaceans with spatial segregation may present differential body coloration depending on the habitat they inhabit. Since crustaceans are unable to synthesize carotenoids, individuals must acquire them from their diet, so diet changes can modify individual coloration. The burrowing crab Neohelice (=Chasmagnathus) granulata inhabits the intertidal, from the uppermost parts of salt marshes to the lowest mudflat zones with a spatial segregation of different size-classes. They are primarily deposit feeders in mud flats and herbivorous–detritivorous in the salt marsh. We analysed the effect of intermoult length on the carapace colour of N. granulata, and the changes in carapace colour with crab size and zone. Crab colour varied between unvegetated and vegetated areas. Some of these differences were in part caused by colour changes related to crab size. Larger crabs show less intensive colours, and given that they inhabit the upper part of the intertidal a differential coloration pattern occurred between zones. In field experiments intermoult duration affected crab colour and some body regions analysed showed differences between zones unrelated to size.

Information

Type
Research Article
Copyright
Copyright © Marine Biological Association of the United Kingdom 2010
Figure 0

Fig. 1. Box-plots comparing intensity values for the red colour band between marsh and mudflat zones for the 6 body regions analysed. Here and thereafter box-plots are constructed with limits of boxes being the 75th and 25th percentile; lines represent 10th and 90th percentiles and squares inside boxes are medians. Inside: t-test results.

Figure 1

Fig. 2. Box-plots comparing intensity values for the green colour band between marsh and mudflat zones for the 6 body regions analysed, with t-test results inside.

Figure 2

Fig. 3. Box-plots comparing intensity values for the blue colour band between marsh and mudflat zones for the 6 body regions analysed, with t-test results inside.

Figure 3

Fig. 4. Correlation analysis between green colour values and crab size for the crab parts with a significant relationship.

Figure 4

Fig. 5. Correlation analysis between blue colour values and crab size for the crab parts with a significant relationship.

Figure 5

Table 1. Correlation analysis between colour values and crab size for the six crab parts analysed. St, sternite; Ab, adomen; 3° Mx, 3° maxilliped; Cap, carapace; Car, carpus; Ch, chela; r2, coefficient of determination ***P < 0.0001; **P < 0.01; *P < 0.5.