Clams belong to a group of invertebrates called mollusks belonging to Mollusca phylum category. There are over 100,000 kinds of animals or species in the Mollusca phylum or category.
Clams are also known as shellfish. Although some shellfish or mollusks only have one shell (like snails), soft shell clams have two shells so they are known as bivalve mollusks. The shells are held together with a hinge. Other bivalves are scallops, oysters, mussels and the hard shell clam or quahog. Squid and octopus are examples of shellfish which have no outside shells.
Soft shell clams live in the intertidal zone, the wet area exposed between high and low tide. Clams are under the water during high tide and are uncovered on the tide flats during low tide. To protect themselves clams burrow down in the mud and sand using their foot. They can burrow more than 11 inches! When the tide comes in, they stick their siphons out and inhale fresh seawater to get oxygen so they can breathe. They also obtain algae, so they can eat. clams live in the sand upside down. Clams eat plankton, and are eaten by small sharks and squid.
Clams can be found both in saltwater and freshwater. Clams can be eaten by people and are found on menus in restaurants that serve seafood. There are over 15,000 different species of clams world wide and the biggest clam is the Giant Clam, Tridacna gigas that can grow up to 4.8 feet long and weigh 550 pounds. Mya arenaria, the soft shell clam, typically measures about 4 inches and weighs less than a quarter of a pound. Soft shell clams are found on the East Coast of the United States from Northern Canada to Cape Hatteras, North Carolina. They also in the Pacific Coast regions of Alaska, Washington, California and in Western Europe.
The shell has 3 layers and 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.