Evolutionary derivation of the American lobster cardiovascular system: an hypothesis based on morphological and physiological evidence

Abstract

The cardiovascular system of the American lobster includes a large muscular heart that pumps blood into seven arteries, each of which ramifies extensively. Portions of the system may be viewed as relatively primitive, while others are highly derived. We have confirmed earlier findings that the sternal artery is not a single vessel, but a paired structure. The sternal artery and its partner closely resemble the medial branches of the segmental lateral vessels from the dorsal abdominal artery in anterior segments of the abdomen, and they may be homologous. We report that the walls of the dorsal abdominal artery contain blocks of striated muscle cells and that the artery can be induced to contract in response to electrical stimulation or perfusion with proctolin. These observations provide the basis for an attempt to trace the evolution of the heart and arteries from that of primitive malacostracans to its state of development in lobsters.