(Latin: a doorlike structure in a passageway that hinders or prevents the reflux or flowing back of its contents)
"Their enlarged gils are covered with cilia (fine hairs) and they have the additional functions of filtering microscopic food particles from the water as it flows over them."
"Bibalves life on the bottom of the sea or lakes and are sedentary or not moving around."valva, "section of a folding or revolving door"; literally, "that which turns"; related to volvere "to roll".
The meaning was extended in about 1659 to "a mechanical device that works like a valve"; and in 1661 in zoology to "halves of a hinged shell".
An oyster is a bivalve because it has a two-valved shell.
"Oysters and mussels, permanently attach themselves to hard surfaces as adults and the foot is sedge-shaped and is used for digging in the sand or mud where they secrete tough attachment threads."
"The plumber turned off the main water valve to the house so he could repair the faucets in the bathroom."2. Part of a hollow organ; such as, the heart, with a flap to make sure fluid goes through it but doesn't come back: "The most important valves in the body are at the exits from the heart chambers and in the veins."
"By making sure that the blood goes in only one direction, these valves are essential to the circulatory system."
"Without the valves, the heart would not be able to function effectively as a pump and the blood circulation could not take place."
"If the valves in the veins in the legs are not functioning properly, it will cause varicose veins, which are swollen and distorted veins that are on the back of the calf or anywhere on the inside of the legs."3. A part of brass-wind instruments for changing the lengths of the movements of air in order to change the pitches of musical tones: "When Mark was playing his trumpet, tuba, French horn, or trombone; he was able to play different notes by manipulating the various valves."
4. Etymology: from Latin valva; usually, the plural form, valvae, "a folding door"; related to volvere, "to roll".
The sense of a membranous fold that regulates the flow of body fluids was first recorded in English in 1615, and then the meaning of a mechanical device which works like a valve, was recorded in 1659.
In zoology, the application of one of the halves of a hinged shell was first presented in 1661.