Habitat-specific shape variation in the carapace of Cyrtograpsus angulatus (Dana, 1851)

IDASZKIN, YANINA LORENA; MÁRQUEZ, FEDERICO; NOCERA, ARIADNA

JOURNAL OF ZOOLOGY (1987)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013

0952-8369

Different environmental and sex conditions induce phenotypic responses (behavioral, morphological and physiological) in many species. The crab Cyrtograpsus angulatus inhabits contrasting intertidal habitats, such as rocky shores and saltmarshes, where they are exposed to a wide diversity of predators. However, their anti-predator responses differ substantially between these two habitats: while crabs in the saltmarshes use or built burrows or they simply hide by burying in the sediment into the tidal channels, on rocky shores they find shelter below rocks, inside crevices, or under seaweeds in tidal pools. Considering that refuges in saltmarshes can be adjusted by the crabs according to their size and the morphology, while in rocky shores they have to fit in the available refuges, we expect that the body shape differs between individuals from each intertidal habitat. In order to test this hypothesis we collected male and female crabs from a saltmarsh and a rocky shore, separated by 3 km, in San José Gulf, Patagonia, and compared the carapace shapes using geometric morphometric methods. The results showed that carapace shape variation is explained by the interaction between sex and habitats. In both sexes, the mean carapace shape on the rocky shore is more slender and more lengthened than in the saltmarsh individuals. Furthermore, the posterior margin of the female carapaces was wider than that of male carapaces, which were slender and more rounded posterolaterally, independent of the intertidal habitat.