Rhithropanopeus harrisii (common names include the Zuiderzee crab,[2]dwarf crab,[2]estuarine mud crab,[3]Harris mud crab,[3]white-fingered mud crab,[4] and white-tipped mud crab) is a small omnivorouscrab native to Atlantic coasts of the Americas, from New Brunswick to Veracruz.[2]
R. harrisii is usually found in brackish water, but can also be found in freshwater. It likes to live on stones and in oyster beds. The crab can reach a maximum size of 20 millimetres (0.8 in). It has an olive-green-brownish color, sometimes with dark spots on its carapace.
R. harrisii was first discovered in Europe in the Zuider Zee, the Netherlands, and is now also found in Denmark, Belgium, Germany, France, Poland, Estonia, Finland, Russia, Portugal, Spain, Italy, Romania and Bulgaria, from the Black Sea and Caspian Sea.[2][6][7]
In the British Isles, R. harrisii has only been observed in Roath Docks, Cardiff, which have lower salinity (12‰) than the surrounding waters.
^Joana Projecto-Garcia; Henrique Cabral; Christoph D. Schubart (2010). "High regional differentiation in a North American crab species throughout its native range and invaded European waters: a phylogeographic analysis". Biological Invasions. 12: 263–263. doi:10.1007/s10530-009-9447-y.
^Terrence Boyle Jr.; Donald Keith & Russell Pfau (2010). "Occurrence, reproduction, and population genetics of the estuarine mud crab, Rhithropanopeus harrisii (Gould) (Decapoda, Panopidae) in Texas freshwater reservoirs". Crustaceana. 83 (4): 493–505. doi:10.1163/001121610X492148.