What is a clam and how do they live? Clam can be a term that covers all bivalves. Bivalves such as oysters and mussels attach themselves to hard objects, and scallops can free swim by flapping their valves together. Some clams bury themselves in sand and breathe by extending a tube to the water’s surface. Those varieties usually possess a stronger foot for digging that looks like a tongue. Clams feed by filtering plankton with their adapted gills, although the digging varieties use their siphoning tubes and more primitive species used special tentacles. Bivalves lack a head or brain and usually have no eyes, although scallops are a notable exception. All bivalves possess a heart, kidneys, a mouth and anus, as well as a circulatory system.
Middle Left Orange Colored Rendering: Ctendonta has smooth surface with fine concentric growth lines and teeth along the hinge plate. Ordovician – Silurian (505 million years ago (mya) to 408 mya)
Top Right Pinkish Colored Rendering: Modiolopsis has asymmetrical thin valves crossed by an oblique depression. Ordovician-Silurian (505 mya to 408 mya)
Middle Bluegreen Colored Rendering: Byssonychia has sharp steeply inclined beak near end of hinge; usually has strong radial ribs. Mostly Upper Ordovician (400 mya)
Top Middle Yellow/Brown Colored Rendering: Goniophora has a lopsided shell with a prominent beak and ridge extending to the rear margin. Silurian – Devonian (438 mya – 360 mya)
Bottom Left Goldish/Brown Colored Rendering: Pteria has thin inequilateral shaped valves with a long straight hinge merging into large unequal wings. Jurassic to recent (245 mya – today)
Bottom Right Tanish/Peach Colored Rendering: Glycimeris has symmetrical circular outline with pointed beak. Cretaceous to Recent (144 mya – today)
Top Left Deep Blue Colored Rendering: Pecten is a genus of many well known bivalves otherwise know as large scallops. Valves have strong radial ribs and are symmetrical except for slightly unequal wings. Mississippian to Recent (360 mya – today)
Bivalves feed the world. Bivalve oysters, scallops and clams are near the bottom of the food chain which many marine and freshwater species depend on for a food source. But don’t forget about land creatures such as otters, for one, and we humans who especially enjoy a treat of clam chowder. Their shells, secreted from calcium carbonate, can be beautiful and are used to adorn our homes in many creative ways.