An '''Open circulatory system''' is a [[circulatory system]] that allows the [[blood]] to flow out of the [[blood vessel]]s and into various body cavities so that the [[cell]]s are in direct contact with the blood.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia | An '''Open circulatory system''' is a [[circulatory system]] that allows the [[blood]] to flow out of the [[blood vessel]]s and into various body cavities so that the [[cell]]s are in direct contact with the blood.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia |