Intestine is mostly used in formation of fecal pellets and the anus opens at the posterior margin of the mantle cavity so that wastes are swept away by the exhalant current. Blood often contains amoebocytes as well as hemocyanin. A contrast with the annelids. The coelomic fluid contains a filtrate of blood filtered through the heart wall as well as the substances secreted into the coelom by glands in the pericardial cavity. This is then subjected to reabsorption and excretion as it passes through the nephridium, which empties waste into the mantle cavity.
Gametes pass to mantle cavity.