Hemolymph or haemolymph's the blood analogue used by all arthropods and most mollusks that've an open circulatory system. In these animals there's no distinction between blood and interstitial fluid. The liquid fills all of the interior (the hemocoel) of the body and surrounds all cells. Muscular movements by the animal during locomotion can facilitate hemolymph movement, but diverting flow from one area to another's limited. When the heart relaxes, blood's drawn back toward the heart through o… (More on Haemolymph)