Oyster

Oysters live in the salt water.

They have two hard shells. These shells stay shut to rest.

Oysters eat by pulling in water. They catch tiny bits of food in the water. This helps them grow.

They also help clean the sea. They filter the water to find food. This makes the water clear for others. Oysters are very helpful to the ocean.

Oysters are animals that live in salt water. They have two hard shells. These shells are called valves.

Oysters are filter feeders. This means they eat by pulling water through their gills. Tiny bits of food get stuck in mucus. The oyster then eats the food.

This way of eating helps clean the ocean. One oyster can filter many liters of water every day. Large groups of oysters form reefs. These reefs are like underwater cities. They give homes to many small animals.

Some oysters are special because they make pearls. A pearl forms when a tiny object gets stuck inside. The oyster covers the object with layers of nacre, which is a shiny material.

Over many years, the nacre builds up into a pearl. Some people even farm oysters to make pearls. This is called aquaculture. Oysters are very important for the health of our seas.

Oysters are amazing salt-water animals known as bivalve molluscs. This name means they have two shells, or valves, that protect their bodies.

Many different families of these creatures live in the ocean or in brackish water. Some people think of them as a special food called a delicacy. Others harvest them for their beautiful shells or the shiny pearls found inside.

They are very important for the health of our oceans. Because they clean the water, they are often called ecosystem engineers.

These animals eat by using a method called filter feeding. They pull water in over their gills by beating tiny hairs called cilia.

Tiny bits of food, like plankton, get stuck in the mucus on the gills. The oyster then moves this food to its mouth to eat. This process also helps clean the water by removing extra nutrients.

An oyster can filter up to 190 liters of water in a single day. In the Chesapeake Bay, large groups once cleaned the entire water volume every few days.

Oysters have a very interesting way of growing and making babies. Most oysters start their lives as males to release sperm into the water.

As they grow larger and store more energy, they change to become females. A single female can produce up to 100 million eggs in one year. These eggs are released into the water to be fertilized. The tiny babies, called larvae, float in the water for a few weeks. Eventually, they settle down on a surface to become young oysters called spat.

Some oysters are famous for making pearls. This happens when a tiny, irritating object gets stuck inside the animal.

To protect itself, the oyster covers the object with layers of a material called nacre. Over many years, these layers build up into a smooth pearl. The color and shape of the pearl depend on the nacre and the object. Some farmers even place a small piece of shell inside to grow a perfect pearl. This takes about three to seven years of careful work.

Oysters create huge underwater structures called reefs.

These reefs are like busy cities for many other sea creatures. Hundreds of animals, like sea anemones and barnacles, live in the nooks between the shells. These reefs also help protect our shorelines from being washed away by waves. People have farmed oysters for a very long time all over the world. In 2005, China produced 80% of the world's oyster harvest.

Today, oyster farming helps provide protein and nutrients to people everywhere.

Oysters are a diverse group of saltwater bivalve molluscs. The term "bivalve" describes animals that possess two shells, known as valves.

These creatures live in marine or brackish habitats across the globe. Many species belong to the superfamily Ostreoidea. Some are highly valued as a culinary delicacy in many cultures.

Others are harvested for their beautiful shells or for the pearls found within their mantles. Because they drastically change their environment, scientists call them ecosystem engineers.

Oysters function as highly efficient filter feeders. They use tiny, hair-like structures called cilia to beat against the water.

This motion draws water over their gills. As water passes through, suspended plankton and other particles become trapped in the mucus of the gill. The oyster then transports this food to its mouth for digestion.

This process also removes excess nutrients like nitrogen and phosphates from the water. An individual oyster can filter up to 190 liters of water every single day. In the past, the Chesapeake Bay oyster population could filter the entire estuary's water volume every three to four days. By 2008, that same cycle was estimated to take nearly a year.

There are several distinct categories of these molluscs. "True oysters" belong to the family Ostreidae. This family includes many edible species, such as the European flat oyster and the Pacific oyster.

Pearl oysters belong to a different family called Pteriidae, or feathered oysters. They are not closely related to true oysters, but they are famous for producing pearls.

Other animals also use the name "oyster" because they look or taste similar. These include thorny oysters, pilgrim oysters, and windowpane oysters. Some of these, like the Tikod amo in the Philippines, are highly prized seafood.

Pearl formation is a fascinating biological process. In nature, a pearl begins when a minute, invasive object enters the oyster. To protect itself, the oyster covers the irritant with layers of nacre, a pearly substance.

Over many years, these layers build up to create a pearl. The shape and color of the pearl depend on the original object and the natural pigments in the nacre. The largest pearl-bearing oyster is the Pinctada maxima, which can reach the size of a dinner plate. In aquaculture, farmers can culture pearls by placing a nucleus, such as a polished mussel shell, inside the oyster. This process typically takes three to seven years to produce a perfect pearl.

Oysters have complex internal anatomy to support their lives. They breathe through their gills and can also exchange gases across their mantles.

A small, three-chambered heart pumps colorless blood throughout the body. Two kidneys located under the adductor muscle remove waste from the blood. While they have a nervous system with nerve cords and ganglia, there is no evidence that oysters possess a brain. Their reproductive systems are also unique. Some species have both eggs and sperm in their reproductive organs. This means it is technically possible for an oyster to fertilize its own eggs.

Reproduction in oysters often follows a pattern called protandry. Most oysters reach sexual maturity within one year. During their first year, they spawn as males by releasing sperm into the water. As they grow larger and gain more energy, they transition to spawning as females.

A single female can produce as many as 100 million eggs in one year. Once fertilized, the eggs develop into veliger larvae. These larvae float in the water for two to three weeks. Eventually, they settle on a surface and become young oysters known as spat. Spat are defined as oysters that are less than 2 centimeters long.

Oyster reefs serve as vital biological hubs. A large group of oysters is known as a bed or a reef.

These reefs can increase the surface area of a flat seabed by ten times. This provides a home for hundreds of species, including sea anemones, barnacles, and mussels. Larger animals, such as striped bass and croakers, use these reefs for hunting. Additionally, these structures act as green infrastructure by protecting shorelines from erosion. Oysters are also important to the global economy through aquaculture. In 2005, China accounted for 80% of the total global oyster harvest.