Functional morphology of the gastric mill of the swimming crab Ovalipes trimaculatus (Decapoda: Portunidae)

Abstract

The stomach of Decapod crustaceans is a complex structure with great interspecific variation. Several studies suggest that the anatomy of the gastric mill varies according to the diet of species in different groups. An alternative view suggests the gastric mill's structure is related to phylogenetic aspects rather than to the diet of a species. The morphology of the gastric mill of Ovalipes trimaculatus, a portunid crab target of fisheries in Argentina and Chile, was studied through stereo-microscope and scanning electron microscope images. Ovalipes trimaculatus has a stomach that corresponds to a macrophagous and predatory diet. The gastric mill is similar to that of other portunids, especially those with predominant animal component in their diet. Our results support the idea that this structure has a basic pattern, given by shape and elements forming the gastric mill; and upon that pattern, trophic habits adaptively shape certain traits.