Class Bivalvia:
Class Bivalvia have following characteristics:
Shell:
They have a shell which consists of two valves. The shell encloses and protects the soft parts of the body.
Shell Structure:
The shells of bivalves are composed of calcium carbonate giving hardness and durability to the shell.
Body Structure:
The body of a bivalve is laterally compressed, with two main regions: the head-foot and the mantle.
Foot:
Bivalves possess a muscular foot that is adapted for various functions like burrowing, digging, or attaching to substrates.
Mantle and Mantle Cavity:
Mantle is a specialized tissue that secretes the shell and creates a mantle cavity which is present between the mantle and the body. The function of mantle cavity is to houses the gills and other respiratory structures.
Gills:
Bivalves have specialized gills that serve for respiration process.
Filter Feeding:
Most bivalves have filter feeding habits. They use their gills for filtering tiny food particles from the water.
Lack of Radula:
Bivalves lack a radula; instead they depend on filter feeding strategies to obtain nutrients.
Reproduction:
Most bivalves reproduce through external fertilization. They often have complex larval stages before settling as adults.
Habitat:
Bivalves inhabit various aquatic environments and can be found in oceans, rivers, lakes and intertidal zones.
Economic Importance:
Bivalves have significant economic importance.
- These are commercially harvested for human consumption e.g. clams, oysters and scallops.
- They play ecological roles in filtering water and providing habitats for other organisms.
Examples of class Bivalvia::
| Scientific Name | Common Name |
| Crassostrea virginica | Eastern Oyster |
| Arctica islandica | Ocean Quahog |
| Pinctada fucata | Akoya Pearl Oyster |
| Ensis spp. | Razor Clam |
| Tridacna gigas | Giant Clam |
| Ostrea spp. | True Oysters |
| Anodonta spp. | Freshwater Mussels |
| Astarte spp. | Boreal Baltic Clam |
| Corbicula fluminea | Asian Clam |
| Venerupis philippinarum | Japanese Manila Clam |
| Chamelea gallina | Pullet Carpet Shell |
| Donax spp. | Wedge Clams |
| Placopecten magellanicus | Atlantic Sea Scallop |
| Mya arenaria | Soft-Shell Clam |
List of Mollusca classes with examples
Phylum Mollusca is classified into seven major classes namely:
- Class Gastropoda
- Class Bivalvia
- Class Cephalopoda (intelligent marine animals)
- Class Polyplacophora (chitons)
- Class Scaphopoda (tusk shells)
- Class Monoplacophora
- Class Aplacophora (worm-like mollusks)