Mollusks

Mollusks are a soft-bodied invertebrates which includes Squids, Octopuses, Snails, Slugs, Ammonites, Clams, Scallops, Mussels, Oysters, and Orthocones. Bivalvia is a group of mollusks that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. Bivalves as a group have no head and they lack some usual molluscan organs like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. The shell of a bivalve is composed of calcium carbonate, and consists of two, usually similar, parts called valves. These are joined together along one edge (the hinge line) by a flexible ligament that, usually in conjunction with interlocking "teeth" on each of the valves, forms the hinge. This arrangement allows the shell to be opened and closed without the two halves detaching. The shell is typically bilaterally symmetrical, with the hinge lying in the sagittal plane. Adult shell sizes of bivalves vary from fractions of a millimetre to over a metre in length, but the majority of species do not exceed 10 cm (4 in). Many Bivalvia are eaten by humans because they been important source of food. They even harvested them for pearls and shells for jewelry, decorations and hobbies. Cephalopods are a group of mollusks with tentacles on their heads and sharp beaks as mouths. They move by expelling water from a tubular siphon under the head. Orthocones and Ammonites are cephalopods with long cone shell and Spiral shell. they can dive very deep thanks to resistance of water pressure. Gastropods are a group of mollusks that have a single, usually spirally coiled shell into which the body can be withdrawn except for slugs. They don't have a shell but they have soft internal shells or prominent mantles.

List of Mollusks

 * Bivalves
 * Clams
 * Mussels
 * Oysters
 * Scallops
 * Oysters
 * Scallops
 * Scallops