ABSTRACT
This chapter deals with the mantle cavity and the structures it contains, and with respiration. The molluscan mantle cavity is one of several enclosed spaces or vestibules found in metazoan taxa that combine respiration with the typical structures and openings seen in cloacae. Bivalves have a single pair of ctenidia enclosed in a very expansive mantle cavity that generally surrounds the entire body and is convergent with the brachiopod condition. Modification of the mantle cavity into a pulmonary sac or ‘lung’ for aerial respiration is found only in gastropods. The roof of the mantle cavity is often provided with one to a few groups of mucus-secreting cell tracts known as hypobranchial glands. Respiration involves the exchange of gases between the animal and the environment. Molluscs undertake anaerobic respiration when either external or internal environments inhibit or prevent normal aerobic respiration.
