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Bivalves have an open circulatory system that bathes the organs in blood . The heart has three chambers: two auricles receiving blood from the gills, and a single ventricle. The ventricle is muscular and pumps hemolymph into the aorta, and then to the rest of the body.
Those bivalves that have siphons, have two of them. Not all bivalves have siphons however: those that live on or above the substrate, as is the case in scallops, oysters, etc., do not need them. Only those bivalves that burrow in sediment, and live buried in the sediment, need to use these tube-like structures. The function of these siphons is ...
Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs , along with freshwater snails . The majority of bivalve molluscs are saltwater species that live in the marine habitats , but a number of families have evolved to live in fresh water (and in some ...
In some mollusks the mantle cavity is a brood chamber, and in cephalopods and some bivalves such as scallops, it is a locomotory organ. The mantle is highly muscular. In cephalopods the contraction of the mantle is used to force water through a tubular siphon, the hyponome , and this propels the animal very rapidly through the water.
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. [1] [2] It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from Greek kardia meaning heart, and Latin vascula meaning vessels).
The coelomic cavity is reduced. They have an open circulatory system and kidney-like organs for excretion. Good evidence exists for the appearance of gastropods, cephalopods, and bivalves in the Cambrian period, 541–485.4 million years ago.
Because of the open circulatory system of gastropods and other molluscs, there is no clear distinction between the blood and the lymph, or interstitial fluid. As a result, the circulatory fluid is commonly referred to as haemolymph, rather than blood. The majority of gastropods have haemolymph containing the respiratory pigment haemocyanin.
In other words, these are metanephridia that are found in some molluscs, for example in the bivalves. Some other molluscs have another type of organ for excretion called Keber's organ. The Bojanus organ is named after Ludwig Heinrich Bojanus, who first described it. The excretory system of a bivalve consists of a pair of kidneys called the ...