Answer
The main disadvantage of an open circulatory system is that it cannot allocate blood to specific tissues in need of oxygen. Under low pressure, the hemolymph moves throughout vessels slowly. Open circulatory systems are necessary for deep sea creatures, such as mollusks which cannot tolerate higher pressures. With open circulation, the organism won't be compressed, despite the great depths in which it lives.
Work Step by Step
In a closed circulatory system, circulating fluid can be directed to areas in need of oxygen and nutrients. Since the fluid never leaves the vessels, this system is more efficient in circulation.
