The Melon Sea Urchin is a sea urchin under the Echinidae family. It can be found in the Mediterranean Sea and in the eastern Atlantic Ocean.
It's cardiovascular system (and that of most sea urchins)
The Melon Sea Urchin has a hemel system. The hemel system contains blood. The main circulation system fills the body cavity. This fluid in the body cavity contains phagocytic coelomocytes, which move through both the hemel and vascular system to other parts of the body.