Wharf Roach - Ligia exotica
Habitat High intertidal to semi-terrestrial areas; most abundant in warm-temperate to subtropical regions, and considerably less prevalent in tropical areas
Range In the United States, L. exotica is found along the Atlantic coast, from New Jersey through Florida; also reported in coastal Texas and Hawaii.
Description Isopod that grows up to 4cm in length; grayish brown to black coloration. Long antennae and uropoda.
Ecological Notes These isopods are usually found under rocks or other pilings above the water line. Ligia exotica is thought to be invasive, although the native range of the species is not certain. Living near the water is important to their survival. The mechanism for water uptake involving the 6th and 7th pair of legs, is unique.
Personal Information While we were looking under rocks at the salt marsh, we saw these scattering around every time we moved a rock.
Journal Articles For information on the water uptake mechanism that Ligia exotica use involving their legs, see:
http://www.biolbull.org/cgi/reprint/213/2/196 Horiguchi H (Horiguchi, Hiroko) et al. (2007). Water uptake via two pairs of specialized legs in Ligia exotica (Crustacea, Isopoda). BIOLOGICAL BULLETIN, 213(2), 196-203.
To understand more about the osmoregulation of Ligia exotica compared to another species in the genus Ligia, see:
http://journals.ohiolink.edu/ejc/tiff2pdf.cgi/Tsai_Min-Li.pdf?issn=03009629&issue=v118i0001&year=1997&article=141_rotsilalttos Tsai ML, Dai CF, Chen HC. (1997). Responses of two semiterrestrial isopods, Ligia exotica and Ligia taiwanensis (Crustacea) to osmotic stress. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-PHYSIOLOGY, 118(1), 141-146.
Contributed by Jessica Parant - 2010