Mollusks

Summary
A lesson on the ocean animals known as mollusks (clams, snails, octopuses, and squid). The reading is accompanied by true/false questions.

Objectives
• To introduce students to the biology of ocean animals called mollusks (clams, snails, octopuses, and squid).

Suggested Grades
6th Grade
7th Grade
8th Grade

Excerpt
Mollusks are a diverse group of animals that belong to the phylum Mollusca. Many members of the mollusk family, like snails and clams, are familiar to most people. Snails are mollusks that occupy a wide variety of environments; various species of snails can be found on land, in fresh water, and in the salt water of the ocean. Other mollusks, like clams, live solely in aquatic habitats, but different species of clams prefer freshwater or salt water habitats. Both snails and clams have a protective outer shell, but other mollusks, like squid and octopuses, do not. Squid and octopuses are mollusks that live only in the salt water of the ocean.

Even though species of mollusks can have very different characteristics, they have enough in common anatomically and developmentally (that is, how they develop from embryo to adult) to be placed in the same scientific category called a phylum. The fossil record includes about 35,000 extinct species of mollusks. Biologists estimate that there are tens of thousands of species of living mollusks, the majority of which are ocean animals.

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