Panopeidae
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.
Panopeus
mud crabs
Panopeus is a genus of mud crabs in the family Panopeidae, distributed primarily in intertidal and estuarine environments of the Western Atlantic. Species within this genus exhibit sexual size dimorphism, with males typically larger than females, and show specialized habitat use patterns including vertical stratification within reef structures. Some species demonstrate extreme male-biased sexual size dimorphism driven by sexual antagonistic coevolution and coercive mating systems. Members of this genus are ecosystem engineers in mangrove and estuarine habitats, influencing sediment structure and energy flow.
Panopeus lacustris
knot-fingered mud crab
Panopeus lacustris, commonly known as the knot-fingered mud crab, is a small true crab (infraorder Brachyura) in the family Panopeidae. It is distinguished by unequal-sized chelae, with the larger claw being exceptionally broad, knobbly, and bearing teeth in the molar area with an immobile finger. The species exhibits sexual dimorphism in size, with males typically larger than females. It is native to the subtropical western Atlantic but has been introduced to Hawaii and the Pacific coast of California. The species serves as a host for the parasitic barnacle Loxothylacus panopaei, which manipulates crab behavior and causes functional castration.