PATTERNS OF HEMOLYMPH-FLOW VARIATION IN DECAPOD CRUSTACEANS

Adult male Dungeness crab, Cancer magister, were trapped in the Barkle y Sound region of Vancouver Island, British Columbia during June 1992 to August 1993. Heart rate and haemolymph flow through the five major arterial systems were recorded in resting undisturbed C. magister usin g a pulsed Doppler flowmeter. This technique allowed calculation of th e stroke volume of the heart as well as cardiac output. The heart rate of 62 C. magister conformed to a normal distribution, whereas haemoly mph flow through individual arteries was exponentially distributed. St able haemolymph flow through all arterial systems was observed in only about 5% of the individuals tested; more often, haemolymph flow in on e or more arteries fluctuated independently of flow through the remain ing arteries. Several typical patterns of variation in cardiovascular parameters are described and related to possible underlying control me chanisms.