Bivalves are found in all oceans and at all depths. They live on the seafloor, buried in the sand or mud, or attached to rocks. Some bivalves, such as scallops and mussels, are able to swim.
Bivalves have two shells that are hinged together at the top. The shells are made of calcium carbonate, which is secreted by the mantle. The mantle is a thin layer of tissue that lines the inside of the shell.
Bivalves have a simple body plan. They have a head, a foot, and a visceral mass. The head is located at the front of the body and contains the mouth and the sensory organs. The foot is located at the bottom of the body and is used for locomotion. The visceral mass is located in the center of the body and contains the digestive organs, the reproductive organs, and the heart.
Bivalves are filter feeders. They use their gills to filter food particles from the water. The gills are located on either side of the body and are covered in tiny cilia. The cilia beat in a wave-like motion, creating a current of water that flows through the gills. The food particles are trapped in the mucus that covers the gills. The food particles are then transported to the mouth by the cilia.
Bivalves are important members of the marine and freshwater ecosystems. They provide food for other animals, such as fish, birds, and mammals. They also help to clean the water by filtering out pollutants.
Some examples of bivalves include:
* Clams
* Mussels
* Oysters
* Scallops
* Cockles
* Razor clams
* Shipworms
* Piddocks
* Fan mussels
* Ark shells
* Pen shells