Ecomorphology of crabs and swimming crabs (Crustacea DecapodaBrachyura) from coastal ecosystems

Abstract

Brachyuran crabs are one of the most diverse taxa of crustaceans, occurring in almost all coastal habitats. Due to their high morphological diversification, the authors sought to ascertain the existence of morphological patterns related to the habitat of coastal brachyuran crabs. We analyzed 17 species from mangrove forests, rocky shores, sandy beaches and exclusively aquatic marine/estuarine ecosystems. A total of 16 linear measurements of males and 17 of females were obtained for each habitat. We were able to discriminate three functional groups of crab species, based on their habitat: 1. Complex Substrates, 2. Semiterrestrial, 3. Exclusively Aquatic. The species belonging to the Complex Substrates group had long ambulatory legs, as well as being heteroquely related to uneven terrain. Semiterrestrial species showed ambulatory legs of different sizes, allowing them to walk easily on the terrestrial terrain due to the long fourth ambulatory leg, and long eyestalks which are important for visual communication. Exclusively Aquatic species showed the largest carapace widths and the shortest eyestalks. The presence of different crab lineages in the environments analyzed allows us to demonstrate the clear evolutionary convergence, by which the crabs adapted to their specific habitat and environment.

Phylomorphometrics reveal ecomorphological convergence in pea crab carapace shapes (Brachyura, Pinnotheridae)

“…Firm homologous structures like skeletons seem to be easier to compare, but soft‐bodied invertebrate taxa pose a problem in this respect. Invertebrates like mollusk bivalves or gastropods have, however, been studied thanks to their hard (partial) exoskeleton (Burridge et al, 2015 ; Potkamp et al, 2017 ; Sherratt et al, 2016 ; Verhaegen et al, 2018 ), but for unknown reasons, crustaceans seem to be underrepresented in the field of eco‐, and phylomorphometrics (with the exception of Marochi & Masunari, 2016 ; Trontelj et al, 2012 ; Vermeiren et al, 2021 ).…”