A clam is a type of shellfish. Clams can be found in saltwater and freshwater. This is a common usage term, and so includes quite a variety of shellfish. Clams are a fairly common form of bivalve, therefore making it part of the phylum Mollusca. There are many clams in the ocean, but some can also be found in some lakes, streams, and rivers.
The word 'clam' is often applied to those that are edible and live amost of their lives halfway buried in the seafloor. Clams have two shells of equal size connected by two adductor muscles and have a powerful burrowing foot.
Clams for cooking do not live attached to rocks (whereas oysters and mussels do). Clams are often got by digging and cooked and served as clam chowder. They may be found on menus in restaurants that serve seafood.
Clams eat plankton, and are eaten by small sharks and squid. Clams have a burrowing foot that they use to dig down into the sand or mud to hide. If you go to the beach and see little holes that appear in the sand each times the waves go away, clams may have made them. Some burrow less than an inch under the sand, while others dig several inches below the surface.
The shell has three layers. The top one is called mother-of-pearl because it is a coating of pearl material.
A living freshwater clam can work like a filter in fish tanks to keep the water clean.
Some clams have life cycles of only one year, while at least one may be over 500 years old. All clams have two calcareous shells or valves joined near a hinge with a flexible ligament, and all are filter feeders.
- "Clam". Encyclopædia Britannica. Encyclopædia Britannica. 2016.
- Danielle Elliot (14 November 2013). "Ming the Clam, World's Oldest Animal, Was Actually 507 Years Old". CBS News. Retrieved 15 November 2013.
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