What Are Bivalves? Brachiopods are benthic (bottom dwelling), marine (ocean), bivalves (having two shells). Lab Questions: 1. Because they have two shells joined at a hinge. 2 Answers. 8. Explain your answer. They have three pairs of ganglia and two pairs of long nerve cords. Bivalves include “more than 15,000 species of clams, oysters, mussels, scallops, and other members of the phylum Mollusca characterized by a shell that is divided from front to back into left and right valves.”. Source(s): https://owly.im/baIqD. Oysters fall into a larger category of similar species called bivalves. Do bivalves show cephalization? Why are they called bivalves? Gill hairs flail the water so it loops through the clam's body. Most bivalves do not have radula because they eat by filtering water through their gills to obtain organic particles. The inshore wrecks are sometimes surrounded by the empty shells of Surf Clams Spisula solidissima, right, to 7" across.Large numbers of the white shells also wash up on beaches. They attach themselves to a firm substrate using secreted threads known as byssal threads, which are produced by the byssal organ of the muscular foot. Anonymous. Each individual shell is called a valve. 4 years ago. Unlike the gastropods that have one shell, or are lacking a shell altogether, bivalves are animals that have two shells, or valves. Clam Dissection Questions Pre-lab: 1. 4 0. bargstadt. Do bivalves show cephalization? It is not only because of the pearls they produce, that bivalves have always been economically important to man. Bivalves include “more than 15,000 species of clams, oysters, mussels, scallops, and other members of the phylum Mollusca characterized by a shell that is divided from front to back into left and right valves.”. 8. Explain your … Continue reading "Clam Dissection Questions" Commonly called bivalves. All bivalves have two shells (the name means "two shells"), and there are about 15,000 species. Mussels are sedentary bivalves. Explain how bivalves obtain nutrients. 3. Is their digestive tract complete or incomplete? 2. They include clams, mussels, oysters and scallops. Bivalves, however, are burrowing specialists and have diversified their ability to move and dig burrows of varying depths. Most bivalves are marine, but about 20% are found in fresh waters. 7. Describe the body of bivalves. These rejected particles are covered in mucus and expelled as so-called "pseudo-faeces". Do bivalves show cephalization? All these simple animals are types of bivalve mollusks: They each have a two-part shell that hinges around a soft invertebrate body inside.Therefore, most ostrovegans can also be called bivalvegans. They first appeared in the Middle Cambrian, about 300 million years before the dinosaurs. 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