Crabs of the species Hemigrapsus oregonensis, when held at temperatures of 5° and 18°C for eight days and then observed at temperatures approximating these holding conditions and at intermediate temperatures, showed greatest locomotor activity and frequency of behaviour patterns at highest temperature conditions. At intermediate temperatures, locomotor activity was greater in crabs from the higher holding condition, and the greatest variability was recorded for females at an observation temperature of 19°C. Observations made at 0530, 1030, 1630 and 2230 hours of the day showed that a peak activity period occurred at 0530 hours in male crabs at most temperature conditions. This may have been caused by the low intensity of illumination used at night. Presentation of chemical food stimuli in the form of a solution of liver to crabs, elicited feeding and probing movements and an increase in locomotor activity. Pieces of art eraser simulating tactile stimuli of meat elicited feeding movements, but no response could be shown to sight of sculpins or minced liver. Visual stimuli appeared ineffective even when combined with other stimuli. Combinations of chemical and tactile stimuli, however, appeared to sum, and responses were increased above those obtained by separate presentation. Starvation increased the frequency of all behavior that occurred as a response to food stimuli. / Science, Faculty of / Zoology, Department of / Graduate