Mussels are mollusks with a hard shell consisting of two valves. They live all over the world, from the Arctic to the Antarctic, and are always in the water. Most live in seawater, even down to 11,000 meters. But there are also mussels in brackish and fresh water, i.e. in lakes and rivers.
There are about 10,000 different types of seashells. Twice as many species are already extinct. From them, there are only fossils.
What do clam bodies look like?
The bowl is on the outside. It consists of two parts. They are connected by a kind of hinge. In the mussel, this hinge is called the “lock”. The shells are hard and contain a lot of lime and other minerals. The inside is covered with a mother of pearl.
The coat encloses the head and intestines. Some mussels are almost closed and have only three openings: water with food and oxygen flows in through one opening, and waste products flow out with the water through the other. The third opening is for the foot.
The head has regressed in the course of evolution. The rasping tongue has also almost completely disappeared. At the edge of the mouth are feelers with eyelashes, which push small pieces of food toward the mouth opening.
In many mussel species, the foot has receded significantly. To do this, it produces a kind of glue in the young mussels, similar to the slime in the snails. With this glue, the mussel can attach itself to the bottom or to another mussel and even detach again.
How do mussels feed?
Mussels suck up water. They filter this in gills like fish. In doing so, they not only extract oxygen from the water, but also plankton. This is their food. They use the feelers to push the plankton into their mouths.
So most mussels absorb a lot of water and release it again. However, this also means that large amounts of poison from the water get into their bodies. This is not only dangerous for the mussels themselves, but also for the people who eat the mussels.
There are also sea shells. They dig into the wood and feed on it. They can destroy entire ships and are therefore very much feared by humans.
Very few mussel species are hunters. They are after small crabs. They suck it in along with a stream of water and digest it.
How do clams live and reproduce?
Most mussel species have males and females. They do not come into contact with each other for reproduction. The males release their sperm cells into the water, and the females their eggs. This is possible because the mussels always live close together.
Sperm cells and egg cells find each other themselves. After fertilization, larvae grow from it. This is a life form between the fertilized egg and the right shell.
Young mussels can move in a variety of ways. Most flip the shells open and closed. This can be compared to the flapping of a bird’s wings. Others stretch out their feet, glue them to the ground and pull their bodies along. Then they loosen the adhesive and stretch out the foot again. A third species sucks in water and expels it quickly. This results in a movement according to the rocket principle.
At the end of adolescence, the mussels look for a suitable place to attach themselves. They spend their adult life there. Especially the mussels and oysters form colonies. But other species do that too. In the process, one shell attaches itself to another.
What is the mother of pearl?
The inside of many mussel shells shines in different colors. This layer is called the mother of pearl. The material is also called the mother of pearl. This actually means that this material is the mother of pearls.
Mother-of-pearl has always been considered valuable. Mother-of-pearl jewelry has been around since the Stone Age. Even before Columbus came to America, shells had the same meaning as our coins. So they were the real currency of the country.
Mother-of-pearl jewelry can be found all over the world. In the past, mother-of-pearl buttons were made and used on shirts and blouses. There are still mother-of-pearl inlays on expensive musical instruments, for example on the neck of guitars, so that the musician can find his way around.
How are pearls formed?
Pearls are round spheres or lumps made of a material very similar to mother-of-pearl. It used to be thought that the mussel used it to wrap grains of sand that got into it, rendering them harmless.
Today, scientists assume that parasites can migrate into the mussel. These are small creatures that want to eat the mussel from the inside. The mussel defends itself by wrapping these parasites in pearly material. This is how pearls are made.
How do people use seashells?
The easiest way is to collect shells in knee-deep water. At low tide, they even often lie on the surface. Otherwise, you have to dive for them.
Mostly the mussels are eaten. The food is similar to fish. People around the world use this food source by the sea. However, the areas are then quickly emptied because mussels grow very slowly.
Some types of mussels are good for farming, especially mussels, oysters, and clams. These mussels also live closely together in nature and form mussel beds. People breed such mussels in suitable enclosures or on trellises. After the harvest, they go to the market.
Anyone who buys a pearl today usually gets a cultured pearl. Only certain types of mussels are suitable for this. You have to open a shell and extract a certain part of the mantle from it. Small pieces of it are then planted in other mussels. A pearl then forms around it. Depending on the type of mussel, this takes a few months to several years.
Can you hear the sea rushing through the shells?
If you hold an empty mussel shell to your ear, you will hear a hissing sound. You can also record this noise with a microphone. So it’s not imagination, but it’s also not the sound of the sea.
An empty conch shell contains air like a trumpet or a guitar. Depending on the form, this air has a vibration that best suits it. We hear this vibration as sound.
The mussel shell picks up all the sounds that come to it from the outside. It absorbs and retains the vibration that best suits its inner form. We hear that as noise when we hold a conch shell to our ears. We hear almost the same noise in the empty shell of a sea snail, perhaps even more clearly. But even with a mug or a cup on the ear, there is a similar noise.