An oyster is a shellfish with two rough white shells that connect together at one point. The oyster has very strong muscles that hold the shell shut. It is very hard for predators such as humans to pry the shell open. An eastern oyster is usually two to six inches long. There is a purple mark that is left behind when the oyster is removed from the shell. The purple mark tells you where the oyster was attached inside the shell. Growth of an oyster can be relatively fast when exposed to warm waters year round. A baby oyster could reach one inch in three months, two inches in seven months, and three inches in fifteen months.
The shell of an oyster is sharp enough to cut through human flesh. Oyster shells are made of calcium carbonate, which is also, know as lime, while the oyster gets the lime from the water that they live in. They also had a kind of skin, which can be referred to as the mantle. The mantle puts calcium carbonate on the outside of the body to form the shell. Oysters have to live in water that s warm year round and not cloudy. The oyster can only grow in places where salt and fresh water mix together (brackish water), for example the Chesapeake Bay. When oysters are born they are free-swimming plankton. When they grow older they find something to attach himself or herself to, for instance debris or a rock pile submerged under the water. Once there shell has grown they are stationary for the rest of their life. When the tide goes out the oyster is fully submerged under the water, however when the tide goes out they are exposed to the air. The oyster shuts its shell tight so that they will not dry out. The shell composes about 80% of the oyster's weight. It is the only means of protection that the oyster has. Unlike the shell of the clam that is hinged at the long, the oyster's shell is hinged at the narrow end.
Oysters are filter feeders. They such in water and filter out plankton or dead plants and/or animal part