Brachyuran
Guides
Dyspanopeus sayi
Say's mud crab, small mud crab
Dyspanopeus sayi is a small mud crab native to the western Atlantic coast of North America, ranging from eastern Canada to Florida. It has become a successful invasive species in European waters, first detected in Wales in 1960 and subsequently spreading to the Mediterranean Sea, North Sea, Black Sea, and most recently the Sea of Azov. The species inhabits muddy bottoms from the intertidal zone to depths of 46 meters and is an active predator of bivalve molluscs and barnacles. It reaches sexual maturity within one year and has a maximum lifespan of approximately two years.
Hemigrapsus
Hemigrapsus is a genus of varunid crabs containing fifteen recognized species. The genus is naturally distributed almost exclusively in the Pacific Ocean, with one species endemic to the Atlantic coast of South America. Two species—H. sanguineus and H. takanoi—have been introduced from East Asia to the North Atlantic region, where they have established invasive populations along European coasts and the eastern United States. One species, H. estellinensis, is considered extinct; it was endemic to a hypersaline spring in the Texas Panhandle.