What Are the Four Main Body Parts of a Mollusk?


For creatures that seem rather tiny in size, mollusks have a rather large importance in the ecosystem and for humans. Served as food by humans and used as decorations, mollusks have long been a part of society. With their importance in mind, it's critical to know what comprises a mollusk. The four main parts of a mollusk are the head, the foot, the visceral mass and the shell it resides in.


  • The head contains all of the sensory organs and the brain of the mollusk. Many mollusks also have a radula, a rough tongue that feels like sandpaper used for feeding. The radula is made of chitin, which also happens to be the same material that arthropod exoskeletons are made of. Some also include magnetite, which gives the mollusks better wear traits.


  • The foot is the muscular part of the body. The foot is used to move around and to dig up food in the dirt for mollusks to eat. The foot causes the body to move by utilizing muscular waves and cilia in combination with mucus.

Visceral Mass

  • The visceral mass houses all the primary organs of the body -- the heart, the nervous system and any other internal organs. Mollusks have well-developed organs and have strong respiratory, nervous and circulatory systems, but do not have defined body segments.


  • The mantle, also known as the pallium, is what secretes the shell. In some mollusks, such as slugs and octopuses, the mantle has no evolutionary value. In other mollusks, the mantle is used for critical activities such as respiration. The shell it creates can be used as protection for the mollusk. Oftentimes when people capture a mollusk, they keep the shell as a piece of art.


  • Photo Credit Jupiterimages/Photos.com/Getty Images
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