Oysters can be described as bivalve molluscs found in many oceans across the world. They have been viewed by lots of folks as an economically valuable animal because they can provide a source of food and pearls, distinctive lustrous objects used in jewelry and ornaments across many cultures. Also, oysters have been found to be effective scrubbers of polluted water, as indicated in several experiments in the United States in 2006. Due to their richness in protein, many other animals have also found them to be very useful.
A mollusc is a soft bodied animal which protects itself with a shell. Bivalves have two shells which are connected with a small hinge. Oysters can open their shells to take in food as well as expel waste substances from their systems, and they can close their shells if threatened by predators. Like other molluscs, oysters have relatively simple biological systems, and they can be found in brackish water as well as salt water.
Oysters belong to the family Ostreidae. They are described as filter feeders, opening their shells to allow water to pass through their gills, supplying them with food and necessary oxygen. Due to their filter feeding nature, they can be used to clean impure water. Oysters tend to root into place on a rock, allowing the tides to fulfill their needs.
Mankind appears to be among the major predators of oysters, although the animals are also eaten by marine animals and organisms like starfish. The relationship between humans and oysters is quite old; many early humans greatly enjoyed oysters since they are relatively easy to harvest and high in nutrition. Some humans regard oysters as delicacy, and raw oysters are often eaten for their supposedly aphrodisiac quality. Oysters may also be cooked in seafood stews and chowders, although they can get rubbery with excessive cooking.
Oyster pearls have been found to be among the most widely harvested around the world, and in some nations people actually farm oysters to cultivate pearls for commercial sale. This is a result of the defensive mechanism employed by oysters when irritants such as rocks or grains of sand enter an oyster shell. It secrets layers of nacre which hardens into a smooth, glossy ovoid shape objects known as pearls.
