Freshwater pearl mussel

This mussel lives in clean rivers.

It has a hard shell. The shell has two parts. These parts stay closed to keep the animal safe. Inside, the shell is white and shiny. It can make pretty pearls. This mussel can live for a very long time. It can live for over 200 years! It uses a big foot to move slowly in the sand. It stays in the water to eat tiny bits of food. This special mussel is very old and wise.

The freshwater pearl mussel lives in clean, fast rivers.

It has a large, heavy shell made of two parts. These parts are joined by a hinge. The shell protects the soft body inside. The inside of the shell is shiny and white. This layer is called nacre.

This mussel can make fine pearls.

These animals live for a very long time. Some can live for 210 to 250 years! They use a large, white foot to move. This foot helps them bury themselves in sand or gravel. They eat by filtering tiny bits of food from the water.

The life cycle of this mussel is very special. It starts as a tiny larva called a glochidium. These tiny mussels must find a host fish to survive. They snap shut on the gills of fish like trout. They grow on the fish until they are ready to drop off. They must land on clean gravel to grow into adults. This mussel is now endangered in many places.

The freshwater pearl mussel is a very special animal. It is a type of mollusc that lives in rivers.

This animal has a shell with two parts joined by a hinge. The shell is large, heavy, and shaped like an oval. It is often yellowish-brown when the mussel is young. As the mussel gets older, the shell becomes darker. Sometimes the older parts of the shell even look worn away. The inside of the shell is covered in a shiny layer called nacre.

This nacre is pearl white and can show many colors. This layer is what allows the mussel to make fine pearls.

This mussel has a very interesting way it works to grow. It starts life as a tiny larva called a glochidium. These larvae are very small, only about 0.6 or 0.7 millimetres long. An adult mussel can release millions of these larvae into the water. The larvae must find a host fish to survive. They look for fish like the Atlantic salmon or sea trout. The tiny larvae snap shut on the fish's gills. They live and grow on the fish until the next spring. Then, they drop off into the river to grow on their own. They must land on clean sand or gravel to stay alive.

Scientists have learned many amazing things about these creatures. A Russian scientist named Valeriy Zyuganov studied them closely. He discovered that these mussels can live for a very long time. He found they could live for 210 to 250 years. Other scientists saw 250-year-old mussels in Finland to prove this. In Europe, the oldest mussel found was in Estonia. That specific mussel was 134 years old when it was caught in 1993. These animals are some of the longest-living invertebrates in the world.

These mussels live in many different places around the globe. They are found in parts of Europe and North America. In the United States, they live in New England. In Canada, they live in the eastern parts. In Europe, they live in countries like Austria and Germany. Some places, like the Czech Republic, have very few left. In Scotland, more than half of the world's young mussels live. However, people have sometimes taken them illegally from the rivers. This makes it harder for the species to stay healthy.

Understanding these mussels helps us understand how rivers work. They live in clean, fast-flowing water. They use a large, white foot to move through the sand. The mussel eats by filtering tiny bits of food from the water. This helps clean the water for other animals in the river. But they need help from fish to complete their life cycle. If the water gets too dirty with silt, the young mussels cannot breathe. They need clean gravel to stay safe and healthy.

The freshwater pearl mussel, known scientifically as Margaritifera margaritifera, is a unique aquatic bivalve mollusc. It belongs to the family Margaritiferidae. This species is considered an endangered animal in many parts of the world.

It plays a vital role in its ecosystem by filtering water. This process can help clarify the water for other living things. Because they are so long-lived, they are some of the most remarkable invertebrates on Earth.

To understand how they live, we must look at their anatomy. Like all bivalves, they have a shell made of two parts. These parts are joined together by a hinge. The shell is large, heavy, and elongated in shape.

When the mussel is young, the shell is usually yellowish-brown. As the mussel ages, the color becomes much darker. Older shells often show signs of corrosion. Inside, the shell is lined with a thick layer called nacre. This is the mother-of-pearl layer.

This nacre is pearl white and can show beautiful, iridescent colors. This layer is also what allows the mussel to produce fine-quality pearls.

The life cycle of this mussel is a complex and difficult process. It begins when an adult releases a mass of one to four million larvae. These tiny larvae are called glochidia. They are very small, measuring only 0.6 to 0.7 millimetres long. Between July and September, the female releases these larvae into the water. Most glochidia will die because they cannot find a host. To survive, they must attach to a specific type of fish. They look for juvenile salmonids, such as Atlantic salmon or sea trout. The glochidia snap shut on the fish's gills. They live there, protected and fed by oxygen, until the following May or June. When they drop off, they must land on clean gravel or sand to grow.

Once they land, the juvenile mussels begin to burrow into the substrate. They use a large, muscular, white foot to move through the sand or gravel. This foot helps them bury themselves to stay safe. Adults typically live with about one-third of their shell exposed to the water. They feed by inhaling water through siphons. They filter out tiny organic particles to get nutrients. This slow growth and feeding process is essential to their survival. They reach maturity at 10 to 15 years of age. After that, they enter a long reproductive period lasting over 75 years.

One of the most amazing facts about this species is its lifespan. The Russian malacologist Valeriy Zyuganov discovered that these mussels exhibit negligible senescence. This means they do not show the typical signs of aging. Zyuganov determined that their maximum lifespan is between 210 and 250 years. These findings were confirmed by observing 250-year-old individuals in Finland. In 1993, an exceptionally old specimen was caught in Estonia. That specific mussel was 134 years old at the time.

The distribution of the freshwater pearl mussel is Holarctic. This means they are found in both the Northern Hemisphere's temperate and Arctic regions. They live on both sides of the Atlantic Ocean. In North America, they are found in eastern Canada and New England. In Europe, they inhabit many countries, including Austria, Belgium, and Germany. Some populations are quite small. For example, in the Czech Republic, the species is critically endangered. In Scotland, more than half of the world's recruiting population lives in over 50 rivers. However, illegal harvesting has caused serious damage to these sites.

Today, many factors threaten the survival of this species. Their numbers are declining in almost every country. Habitat degradation is a primary cause of this decline. Human activities like river regulation, drainage, and sewage disposal change the water. Water pollution and the introduction of excess nutrients also cause harm. If the river bottom becomes clogged with silt, the young mussels cannot get oxygen and will die. They require clean, fast-flowing streams to thrive. Furthermore, the introduction of exotic fish species can reduce the number of native hosts available for the larvae. The invasion of the zebra mussel is another serious threat to their environment.