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9.9: Importance of Mollusks

Difficulty Level: At Grade Created by: CK-12
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Where do pearls come from?

Pearls are highly valued as gemstones. Most gemstones come from the earth, but pearls come from living things. They are created by mollusks, such as oysters.

Importance of Mollusks

Mollusks are important in a variety of ways, including as food, for decoration, in jewelry, and in scientific studies. They are even used as roadbed material and in vitamin supplements.

Mollusks as Food

Edible species of mollusks include numerous species of clams, mussels, oysters, scallops, marine and land snails, squid, and octopuses. Many species of mollusks, such as oysters, are farmed in order to produce more than could be found in the wild (Figure below).

An oyster harvest in France

An oyster harvest in France.

Mollusks in Decoration and Jewelry

Two natural products of mollusks used for decorations and jewelry are pearls and nacre. A pearl is the hard, round object produced within the mantle of a living shelled mollusk. Natural pearls have been highly valued as gemstones and objects of beauty for many centuries. The most desirable pearls are produced by oysters and river mussels. Natural pearls form when a foreign object gets trapped in the shell. It's as if the mollusk has a splinter. The mollusk reacts by covering up that irritant. This is the process that creates a pearl.

Nacre, or mother of pearl, is an iridescent inner shell layer. It can be found in buttons, watch faces, knives, guns, and jewelry. It is also used as decorations on various musical instruments.

Mollusks in Scientific Studies

Several mollusks are ideal subjects for scientific investigation of the nervous system. The giant squid has a sophisticated nervous system and a complex brain for study. The California sea slug, also called the California sea hare, is used in studies of learning and memory, because it has a simple nervous system, consisting of just a few thousand large, easily identified neurons. These neurons are responsible for a variety of learning tasks. Some slug brain studies have even allowed scientists to better understand human brains!


  • nacre: Or, mother of pearl, is an iridescent inner shell layer.
  • neuron:
  • oyster: Mollusks with a rough irregular shell that live in coastal waters and provide a food source.
  • pearl: Hard, round object produced within the mantle of a living shelled mollusk.


  • Some mollusks, such as oysters and scallops, are important food sources.
  • Mollusks are used for decoration and are important in scientific studies.


Use the resources below to answer the questions that follow.

  1. What large tubular structures did Professor Young find in squids? How big were these tubular structures?
  2. Why were the size of these structures important to Professor Youngs work?
  3. What did scientists discover when they were able to empty the contents of a squid axon?
  4. How did World War II help the study of neuron functioning?
  5. How are the nervous systems of cephalopods similar to the nervous system of mammals?
  1. How are natural pearls made?
  2. How are cultured pearls made?


  1. Name two mollusks that are used for food.
  2. Where do pearls come from?
  3. What makes the California sea slug ideal for studies of learning and memory?

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Or, mother of pearl, is an iridescent inner shell layer.


Nerve cell.


Mollusk with a rough irregular shell; lives in coastal waters and provides a food source.


Hard, round object produced within the mantle of a living shelled mollusk.

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Difficulty Level:
At Grade
7 , 8
Date Created:
Nov 29, 2012
Last Modified:
Aug 30, 2016
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