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This figure shows several of the much more common and familiar mollusks.

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Structure and function of Mollusks

Mollusks room a an extremely diverse phylum. Part mollusks are practically microscopic. The largest mollusk, a colossal squid, might be as lengthy as a college bus and also weigh over fifty percent a ton! The straightforward body plan of a mollusk is shown in Figure below. The main separating feature is a difficult outer shell. That covers the height of the body and also encloses the inner organs. Most mollusks have actually a distinctive head region. The head may have tentacles because that sensing the environment and also grasping food. There is normally a muscular foot, which might be offered for walking. However, the foot has evolved adjustments in many species to be offered for other purposes.


Basic Mollusk body Plan. The basic body plan shown right here varies amongst mollusk classes. Because that example, number of mollusk varieties no longer have actually shells. Perform you understand which ones?

Two unique features of mollusks are the mantle and radula (see Figure above). The mantle is a great of organization that lies between the shell and the body. That secretes calcium carbonate to form the shell. It forms a cavity, dubbed the mantle cavity, in between the mantle and also the body. The mantle cavity pumps water because that filter feeding. The radula is a feeding body organ with teeth made the chitin. The is located in prior of the mouth in the head region. Herbivorous mollusks usage the radula to scrape food together as birds off rocks. Predatory mollusks usage the radula come drill holes in the shells of your prey.

Mollusks have actually a coelom and a complete digestive system. Their excretory system is composed of tube-shaped organs called nephridia (see Figure above). The organs filter waste from human body fluids and also release the waste right into the coelom. Terrestrial mollusks exchange gases with the surrounding air. This occurs across the lining the the mantle cavity. Aquatic mollusks “breathe” under water with gills. Gills are thin filaments that absorb gases and exchange them in between the blood and surrounding water.

Mollusks have actually a circulatory mechanism with one or two hearts the pump blood. The heart is a muscular organ that pumps blood with the circulatory mechanism when its muscle contract. The circulatory system may be open up or closed, depending on the species.

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The significant classes of mollusks vary in structure and also function. You can read around some the their differences in Figure below.