Walking Around Underwater and Fighting Infection: Cardiovascular and Respiratory Function in Lobsters and Blue Crabs
Darwin D. Jorgensen, Dept. of Biology, Roanoke College
28 Mar 2008
In crabs and lobsters, the cardiovascular and respiratory systems are intimately associated. Each gill chamber (a confined space into which the gills extend) is ventilated by the action of a negative-pressure pump that, quite literally, sucks water past the gills. The pump is capable of operating over an extensive output range and, hence, hydrostatic pressure in a gill chamber can be quite variable. A single ventricle generates pressure to move hemolymph through the circulatory system, including the small-diameter hemolymph channels that course through the gills. While the movement of hemolymph through the circulatory system is dynamic, hemolymph pressure is quite low. We are interested in the relationship between ventilatory pump function, gill chamber pressure, and hemolymph pressure/flow in the circulatory system, particularly the gill circuit. Our work on physiological support of exercise in these animals gives us a relevant way to assess the effect of variable ventilatory pump function on circulation. The gills in crabs and lobsters (in addition to serving as gas exchange devices) also appear to work as immune organs, and we have become interested in the ways bacterial infection impacts cardio-respiratory function in these animals.