Circulation/Internal Transport

Arthropods have a well developed heart that pumps blood through an open circulatory system. In the terrestrial arthropods they have a heart that is stretched along the abdomen, while in the aquatic arthropods their hearts are smaller and located in the center of their bodies. As the heart contracts, blood travels through the body and then leads back to a cavity around the heart and re-enters through openings.

A cool site for aquatic circulatory system (lobster) please click image below: