Portunid
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Callinectes sapidus
blue crab, Atlantic blue crab, Maryland blue crab
Callinectes sapidus is a large portunid crab native to the western Atlantic Ocean and Gulf of Mexico, with established invasive populations in Europe, Asia, and elsewhere via ballast water transport. The species exhibits pronounced sexual dimorphism in abdominal shape and claw coloration. It supports major commercial fisheries, particularly in the Chesapeake Bay and Gulf of Mexico, though populations have declined in some areas due to overfishing and environmental degradation. As an invasive species, it damages fishing gear and competes with native species in introduced ranges.