Does feeding limit cardiovascular modulation in the Dungeness crab Cancer magister during hypoxia?
Decapod crustaceans inhabit aquatic environments that are frequently subjected to changes in oxygen content. The physiological mechanisms that allow them to cope with periodic episodes of hypoxia have been well documented. Most crustaceans exhibit a bradycardia coupled with diversion of haemolymph from digestive organs towards ventral structures. However, all these experiments were conducted on animals that were starved prior to experimentation in order to avoid increases in metabolism associated with digestive processes. The present study sought to determine how the Dungeness crab Cancer magister balances the demands of physiological systems when they feed and digest in hypoxia. Cardiac parameters and haemolymph flow rates through each arterial system exiting the heart were measured using a pulsed-Doppler flowmeter. Scaphognathite beat frequency (ventilation rate) was calculated by recording changes in pressure in the branchial chamber. There was an increase in both cardiac and ventil
