haemo- (relation or resemblance to blood, association with blood;) - coel (An internal fluid-filled body cavity (other than the gut) within an organism, it lies between the gut
(derived from the endoderm) and the outer body wall (derived from the ectoderm) and is lined entirely with tissue derived
from the mesoderm )
The haemocoel is the main body cavity of many invertebrates, including insects, formed from an expanded 'blood', or haemolymph, system.