Geotactic responses of male freshwater field crab,Oziotelphusa senex senex have been studied with reference to salinity adaptation. The crabs exhibited a stereotyped walking behaviour. The pairsL 2 R 3,L 3 R 2,L 4 R 1 andL 1 P 4 comprising left and right walking legs were used for the movement in reciprocating fashion. The weight of the crab influenced the orientation angle significantly. Blinding of the eyes did not affect the orientation. Irrespective of the inclination angle, the salinity adaptation reduced the walking rates. All these results have been discussed in terms of the greater scope and potential for escape, available in salinity adapted individuals.