What is gaffing for mussels


This picture shows how different mussels can be. These bowls are all from the sea.

Clams are molluscs with a hard shell that consists of two flaps. They live all over the world, from the Arctic to the Antarctic, and always in the water. Most of them live in sea water, even up to 11,000 meters deep. But there are also mussels in brackish water and in fresh water, i.e. in lakes and rivers.

There are around 10,000 different types of clams. Twice as many species are already extinct. There are only fossils left of them.

What do mussel bodies look like?

This mussel has opened the shells and shows the soft tissues inside.

The shell is on the outside. It consists of two parts. They are connected by a kind of hinge. This hinge is called the “lock” on the shell. The shells are hard and contain a lot of lime and other minerals. The inside is covered with mother-of-pearl.

The coat encloses the head and the bowels. In some mussels it is almost closed and has only three openings: water with food and oxygen flows in through one opening, while in the other the waste materials flow out again with the water. The third opening is for the foot.

The head has receded in the course of evolution. The rasp tongue has also almost completely disappeared. At the edge of the mouth there are buttons with eyelashes that push small pieces of food towards the mouth opening.

In many types of mussels, the foot has receded significantly. To do this, it produces a kind of glue in young mussels, similar to the slime in snails. With this glue, the mussel can attach itself to the bottom or to another mussel and even loosen it again.

How do mussels feed?

The marine drill shell feeds on wood.

Mussels suck in water. They filter this in gills like fish. In doing so, they not only get oxygen from the water, but also plankton. That is their food. With the buttons they push the plankton into their mouths.

Most mussels take in a lot of water and give it off again. However, this also causes large amounts of poison from the water to get into their bodies. This is dangerous not only for the mussels themselves, but also for the people who eat the mussels.

There are also drill clams. They dig into the wood and feed on it. So they can destroy entire ships and are therefore very feared by the people.

Very few species of mussels are hunters. They are after little crabs. They suck in these together with a stream of water and digest them.

How do mussels live and multiply?

A prickly oyster in the waters off the Fiji Islands

Most species of mussels have both males and females. They do not come into contact with each other for reproduction. The males release their sperm cells into the water, the females their egg cells. This works because the mussels always live close to one another.

Sperm cells and egg cells find each other themselves. After fertilization, larvae grow from it. This is a way of life between the fertilized egg and the real clam.

Young clams can move in a number of ways. Most of them open and close the bowls. You can compare it a little with the flapping of the wings of birds. Others stretch out their feet, glue them to the ground and drag their bodies. Then they dissolve the glue and stretch out the foot again. A third type sucks in water and expels it quickly. This results in a rocket principle movement.

At the end of adolescence, the mussels look for a suitable place to anchor themselves. This is where they spend their adult lives. The mussels and oysters in particular form colonies. But other species do that too. In the process, one mussel attaches itself to another.

What is mother-of-pearl?

The inside of this freshwater shell shows a layer of mother-of-pearl.

The inside of many mussel shells shines in different colors. This layer is called mother-of-pearl. The material is also called mother-of-pearl. What is actually meant is that this material is the mother of pearls.

Mother-of-pearl has always been considered valuable. Mother-of-pearl jewelry has existed since the Stone Age. Even before Columbus came to America, shells had the same meaning there as our coins. So they were the actual currency of the country.

Mother-of-pearl jewelry can be found all over the world. In the past, buttons were made from mother-of-pearl and used on shirts and blouses. Expensive musical instruments still have inlays made of mother-of-pearl, for example on the neck of guitars, so that the musician can orientate himself well.

How are pearls made?

A black pearl in its shell.

Pearls are round balls or misshapen structures made of a material that is very similar to mother-of-pearl. It used to be thought that the mussel would use 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 shell from the inside. The clam defends itself by wrapping these parasites in pearl material. This is how pearls are made.

How do people use mussels?

The easiest thing to do is to collect mussels in knee-deep water. When the tide is out, they are often on the surface. Otherwise you have to dive for them.

Usually the mussels are eaten. The food is similar to fish. People by the sea use this food source all over the world. However, the areas are then quickly emptied, as mussels only grow very slowly.

Some types of mussels are good for breeding, especially mussels, oysters and clams. These mussels also live closely together in nature and form mussel banks. People breed such mussels in suitable enclosures or on grids. After the harvest, they come onto the market.

Anyone who buys a pearl today usually receives a cultured pearl. Only certain types of mussels are suitable for this. You have to open a shell and remove a certain part of the shell 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 sound of the sea in the shells?

If you hold an empty conch shell to your ear, you will hear a rustling. You can also record this noise with a microphone. So it's not an imagination, but neither is it the sound of the sea.

An empty conch shell contains air like a trumpet or a guitar. Depending on the shape, this air has a vibration that suits it best. We hear this vibration as a sound.

The conch shell absorbs all sounds that come from outside. It picks up the vibration that best suits its internal shape and keeps it. We hear this as noise when we hold a conch shell to our ear. 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 to the ear, there is a very similar noise.

  • Petrification of an extinct species of mussel

  • Altar with a mother-of-pearl relief, from Germany, about 500 years old

  • Some 400 years ago someone painted this painting with oysters, front left.

  • A cut open mussel

  • Mother-of-pearl is not only found in mussels, but also in sea snails, even more colorful.