Mechanism of Coagulation in Gecarcinus lateralis

Agglutination of cells, degranulation, and loss of cellular membranes compose the major form of coagulation in the hemolymph of Gecarcinus lateralis. It is only after agglutination of the formed elements of the hemolymph that fibrin-like strands appear. Sodium citrate, in a concentration of 10% or more to prevent coagulation, is always inadequate to prevent cell agglutination. Multiple studies by protein electrophoresis failed to reveal any differences between plasma and serum, nor did they allow us to identify a soluble protein in plasma that did not appear in serum. Crab hemolymph changes in its capacity for clotting during the molt cycle, with the most rapid clotting occurring in the premolt period. A new protein appears in the premolt period, but its relation to the whole clotting mechanism is unknown. In contradistinction to vertebrate systems, citrated hemolymph does not clot when calcium is added. There is no relationship that can be demonstrated between activating systems in vertebrate plasma and clotting in the crab. It would seem that, rather than the vertebrate coagulating system evolving from the crustacean type of clotting system, the development of these clotting systems has run in parallel. The crustacean cell, in addition, appears to be more potent than vertebrate cells in clotting systems. The comparison of human lymph to crustacean hemolymph would indicate that, for a given amount of cells, crustacean hemolymph clots 2 to 20 times faster than human lymph. On the other hand, agglutination of cells is a fundamental initiating step in coagulation of both human blood and crustacean hemolymph.