Behavioral Responses of the Crab Hemigrapsus Oregonensis to Temperature, Diurnal Light Variation and Food Stimuli

Abstract

Crabs of the species Hemigrapsus oregonensis when held at temperatures of 5 and 18°C for eight days and then observed at temperatures approximating their own holding conditions and at intermediate temperatures showed greatest locomotor activity under highest temperature conditions. At intermediate observation temperatures, locomotor activity was greater in crabs from the higher holding condition. The greatest variability was recorded for females held and observed at the highest temperatures. Observations made at four times of day showed that a peak activity period occurred at 0530 hr in male crabs at most temperature conditions. This may have been caused by the low illumination used at night. Feeding and probing movements and an increase in locomotor activity resulted from the presentation of chemical food stimuli in the form of a solution of liver. Tactile stimuli from pieces of art eraser released feeding movements, but sight of sculpins or minced liver caused no measurable feeding response. Visual stimuli appeared ineffective even when combined with chemical and tactile food stimuli, but combining the chemical with the tactile stimuli increased responses above those obtained by separate presentation. Starvation increased the frequency of all behavior that occurred in response to food stimuli.