Swan Mussel

Swan mussle belongs to a group of molluscs called Bivalves (Bivalvia). Bivalves have their body coved by two shells. Shells are held firmly closed by adductor muscles. They are opened automatically without energy by an elastic tendon. It is the reason why dead mussels are always found with open shells, because adductor muscles holding them together stop doing so. Food supply, as well as breathing, is supplied by a flow of water that enters a body cavity by incurrent siphon located at the rear part of the body. Water flows through gills and saturates them with oxygen. Apart from oxygen, there are final food particles in the water, they are filtered by gills as well. Their particles are glued together by slime and transported by cilia to swan´s mouth. Digestion system is differentiated in a mouth, pharynx, stomach with digestive gland (hepatopancreas) and a gut that opens in the excurrent siphon. The circulatory system is open with a hearth enclosed in the pericardium. The pericardium is connected to the pair of kidneys. The nervous system is reduced to three ganglions. Mussels are gonochorists, i. e. their sexes are separated, with a larval stadium called a glochidium. Glochidium firstly develops on gills of their parent but later parasitises skin or gills of fishes.