MCGAW, I.J.; University Of Nevada, Las Vegas: Cardiovascular Dynamics of Postprandial Dungeness Crabs, Cancer magister, During Hypoxic Exposure

Decapod crustaceans react to hypoxia with a pronounced bradycardia and diversion of hemolymph to ventral structures. In contrast, when they feed there is an increase in both cardiac and respiratory variables. The question then arises, as to how crustaceans balance the demands of these physiological systems when they feed and digest in hypoxia. Cardiac function and hemolymph flow was monitored in intact Dungeness crabs, Cancer magister, during and following feeding in hypoxic (3.2 KPa) conditions. Most noticeably, the bradycardic response to hypoxia was reduced by food intake. Postprandial crabs maintained blood flow to digestive organs during hypoxia by diverting it away from ventral regions. During a recovery phase in normoxia there was a large increase in cardiac variables and hemolymph flow rates, with blood being diverted to the digestive structures. Clearly the nutritional state of an animal is important in modifying physiological responses to environmental perturbations.