Dr. Iain McGaw
Mcgaw, I.J.; Stillman, J.H. (2010). Cardiovascular system of the Majidae (Crustacea: Decapoda). Arthropod Structure & Development. 39 (5) 340-349.
The cardiovascular system of majid crabs was mapped using corrosion casting techniques. the general form of the circulatory system was comparable to that of other malacostracan crustaceans, but with distinct differences between several arterial systems. the anterior aorta exited from the anterior surface of the heart supplying hemolymph to the antennae, eyestalks, gastric muscles and brain. this artery was more complex compared with other decapods. the anterolateral arteries exited from the anterior dorsal surface of the heart and supplied hemolymph to the hypodermis, stomach, antenna! gland and mandibular muscles. the hepatic arteries were larger and more complex compared with other decapod families, branching profusely within the hepatopancreas and gonads. the small posterior aorta exited from the posterior-ventral surface of the heart. standard sex-specific differences in this artery were observed. exiting from the ventral surface of the heart, the sternal artery supplied each pereiopod in a segmental arrangement. the sternal artery arrangement was different to other brachyuran crabs, possibly a symplesiomorphy with segmented ancestors. in accordance with anatomical descriptions of blue crabs and cancer crabs it would also seem appropriate to classify the circulatory system of the majidae as one that is "incompletely closed". crown copyright (c) 2010 published by elsevier ltd. all rights reserved.
Curtis, D.L.; Vanier, C.H.; Mcgaw, I.J. (2010). The effects of starvation and acute low salinity exposure on food intake in the Dungeness crab, Cancer magister. Marine Biology. 157 (3) 603-612.
Adult Cancer magister make forays into hyposaline estuarine habitats during times of high food abundance. However, as weak osmoregulators, they are poorly equipped to deal with the concurrent demands of osmoregulation and digestion. Therefore, the potential interaction between nutritional status and feeding in a physiologically challenging environment was investigated. Changes in the proportion of crabs feeding, the amount of food consumed, the time spent feeding, and the efficiency with which a meal was consumed were examined in response to the length and severity of hyposaline exposure, and the duration of starvation. Reductions in the (a) number of animals feeding, (b) the amount of food consumed, and (c) the time spent feeding were observed in salinities where C. magister actively osmoregulates the concentration of its internal fluids. Although this reduction in feeding was likely a stress response, the crabs were able evaluate the level of salinity stress: there was a dose-dependent reduction in feeding, and they were able to discriminate between salinities separated by as little as 3.5aEuro degrees. The likelihood that animals would feed in low salinity increased with starvation. Thus, the aversion to food uptake in physiologically stressful conditions may be overridden by the need to procure nutrients. In the natural environment, we suggest that C. magister are employing an 'eat and run' strategy, moving into the estuary, consuming a meal, and retreating to higher salinities to digest.
