The main body cavity in the Phylum Mollusca is called the?

Mollusca are in broadened terms coelomates, or animals with a true coelom. This means their gut is suspended by mesenteries in a fluid filled cavity called the coelom. However, cephalopoda, or squids and octopi, are the only mollusks with a closed circulatory system so they are have TRUE coeloms. All the other classes of mollusca are what are known as hemocoels because of their lack of a pericardium and open circulatory. Hemoceols still have true coeloms, they're merely reduced in ceomplexity. The coeloms of cephalopds are the same complex system found in humans, whereas the hemocoels are more commonly found in annelids, or earth worms, and other primative phylums.