ORIENTATION TOWARD NATURAL AND ARTIFICIAL GRASSBEDS BY SWIMMING BAY SCALLOPS, ARGOPECTEN-IRRADIANS (LAMARCK, 1819)

The orientation of swimming in bay scallops was studied in the field u sing natural and artificial grassbeds as potential directional cues. S callops released on sand 25 cm from a natural grassbed swam toward the grassbed regardless of the grassbed's direction relative to the scall op's facing direction. When tested with an artificial grassbed, scallo ps released on sand 25 cm away also swam toward the grassbed; however, the swimming of scallops released 50 cm away from the artificial gras sbed was randomly oriented, as was also true for control scallops rele ased on sand 4 m away. Under natural conditions, bay scallops appear a ble to orient their swimming based on visual information, as well as t he direction where chemical stimuli are contacted, as previously repor ted.