Mussel - Invertebrate inhabitants of reservoirs from the family of bivalves. They live all over the world in fresh + brackish + salty water bodies. Animals settle in coastal areas with cool water and a fast current. Mussels massively accumulate near the coastal zones - a kind of mussel banks that create a strong filtration of water.
Origin of view and description
Mussel is a common name that applies to members of the families of bivalve mollusks living in fresh and salt water. The members of these groups have a common shell with an elongated contour, which is asymmetric in comparison with other edible mollusks, the outer shell of which has a more rounded or oval shape.
The word "mussel" itself is used colloquially to refer to mollusks of the Mytilidae family, most of which live on the open shores of the coastal zone of water bodies. They are attached by strong bisalkal filaments to a solid substrate. Some species of the genus Bathymodiolus are equipped with colonized hydrothermal vents associated with ocean ridges.
In most mussels, shells are narrow but long and have an asymmetric, wedge-shaped shape. The outer colors of the shells have dark shades: often it is dark blue, brown or blackish, and the inner coating is silver and somewhat pearly. The name "mussel" is also used for freshwater bivalve mollusks, including freshwater pearl mussels. Mussels living in fresh water belong to different subclasses of bivalve mollusks, although they have some surface similarities.
Freshwater mussels of the Dreissenidae family are not assigned to the previously designated groups, even if they resemble them in shape. Many species of Mytilus live attached to stones using byssus. They are classified as Heterodonta, a taxonomic group that includes most species of bivalve mussels called “mollusks”.
Appearance and features
Photo: What does a mussel look like?
The mussel is characterized by a smooth, uneven outer shell, usually purple, blue or dark brown, with concentric lines of growth. The inside of the case is pearl white. The inner part of the valves has a whitish-yellow color, the scar of the posterior adductor is much larger than the front adductor. Brown fibrous filaments extend from the closed sheath for attachment to the surface.
The length of the mature shells is about 5-10 cm. They have an oblong oval shape and consist of the right and left cusps, which are fastened by an elastic muscular ligament.
The shell consists of 3 layers:
- top made of organic material;
- medium thick layer of lime;
- inner silver-white pearl layer.
Mussels have a sphincter, which is located in the soft part of the shell and other organs (heart, stomach, intestines, kidney). With the help of the sphincter, the mussel can tightly close the shells in case of danger or drought. Like most bivalves, they have an organ called the leg. In freshwater mussels, the foot is muscular, large with a byssal gland and usually in the shape of an ax.
Interesting fact: A foreign body, which is between the sash and the mantle, is enveloped on all sides with mother-of-pearl, thereby forming pearls.
Iron, with the help of egg white contained in mussel and iron filtered from the sea, produces byssus strands with which the mussel can cling to the surface. The foot is used to stretch the animal through a substrate (sand, gravel or silt). This is due to the leg moving through the substrate, widening the passage, and then pulling the rest of the animal with the shell forward.
In sea mussels, the leg is smaller in shape and similar to the tongue, with a small indentation on the abdominal surface. A viscous and sticky secret is secreted from this hole, which enters the groove and gradually hardens upon contact with sea water. What forms unusually rigid, strong, elastic threads with which the mussel is attached to the substrate, remaining motionless in places with an increased flow.
Where does the mussel live?
Photo: Mussels in Russia
Mussels are found in coastal areas of the northern Atlantic Ocean, including North America, Europe and the northern Palearctic. They are found from the White Sea in Russia to the south of France, on all the British Isles, in northern Wales and western Scotland. In the western Atlantic, M. edulis occupies the southern Canadian marine provinces up to North Carolina.
Sea mussels are located in the middle and lower tidal zone in the relatively temperate seas of the world. Some mussels are located in tropical tidal zones, but not in such large numbers.
Some species of mussels prefer salt marshes or quiet bays, while others enjoy a rumbling surf, covering the coastal stones washed with water. Some mussels have mastered depths near hydrothermal vents. The South African mussel does not stick to the rocks, but hides on sandy beaches, located above the surface of the sand for food, water and waste.
Interesting fact: Freshwater mussels live in lakes, canals, rivers and streams around the world, excluding the polar regions. They constantly need a source of cool, clear water. Mussels choose water containing minerals. They need calcium carbonate to build their shells.
The mussel can resist freezing for several months. Blue mussels acclimatize well in the t range from 5 to 20 ° C, with an upper stable limit of thermal stability of about 29 ° C for adults.
Blue mussels do not thrive with water salinity of less than 15%, but can withstand significant environmental fluctuations. Their depth ranges from 5 to 10 meters. Usually M. edulis is found in the sublittoral and littoral layers on rocky shores and remains permanently attached there.
Now you know where the mussel is found. Let's see what this mollusk eats.
What does mussel eat?
Photo: Black Sea mussels
Sea and freshwater mussels - filter. They have two holes. Water passes through an inlet in which the eyelash hairs create a constant flow of water. Thus, tiny particles of food (plankton of plants and animals) adhere to the mucous layer of the gills. Then the eyelashes promote the mucus of the gills with particles of food into the mouth of the mussel and from there into the stomach and intestines, where the food is finally digested. Non-digested residues are again discharged from the outlet along with breathing water.
The main diet of mussels consists of phytoplankton, dinoflagellates, small diatoms, zoospores, flagellates and other protozoa, various unicellular algae and detritus, filtered from the surrounding water. Mussels are filtering devices for suspension filters and are considered garbage collectors collecting everything in the water column that is small enough to absorb.
The usual diet of mussels can be attributed to:
Sea mussels are often found stuck together on a wave-washed stone. They are attached to the rocky ledges with their byssus. The habit of sticking contributes to the retention of mussels when exposed to strong waves. At low tide, individuals in the middle of the cluster are subject to less fluid loss due to the capture of water by other mussels.
Features of character and lifestyle
Photo: Sea mussels
Mussels are a sedentary species that constantly settles on substrates. Mature mussels prefer a sedentary pastime, so their leg loses its motor function. In loose substrates, younger individuals strangle older mussels on which they settle.
Interesting fact: Mussels are used as bio-indicators for monitoring the state of the environment in fresh and sea water. These mollusks are very useful because they are common throughout the world. Their characteristics ensure that they demonstrate the environment in which they are located or placed. Changes in their structure, physiology, behavior or abundance indicate the state of the ecosystem.
Special glands secrete strong protein threads, with which they are fixed on stones and other objects. River mussels do not possess such an organ. At the mussel, the mouth is at the base of the leg and is surrounded by lobes. The mouth is connected to the esophagus.
The mussel is highly resistant to elevated sediment levels and helps remove sediment from the water column. Mature mussels provide habitat and prey for other animals and serve as a substrate for the attachment of algae, increasing local diversity. Mussel larvae are also an important food source for plantation animals.
Mussels have special devices to help in geolocation and orientation. Mussels have chemoreceptors capable of detecting gamete release. These chemoreceptors also help teenage mussels to avoid temporary settling on substrates near mature mussels, apparently to reduce competition for food.
The life span of these mollusks can vary significantly depending on the location of attachment. Settlement in more open coastal zones makes individuals significantly more vulnerable to predators, mainly birds. Mussels that settle in open places can experience mortality rates of up to 98% per year. Drifting larval and juvenile stages suffer from the highest mortality rates.
Social structure and reproduction
Every spring and summer, females lay five to ten million eggs, which are then fertilized by males. Fertilized eggs turn into larvae, which are consumed by predators by 99.9% during a four-week development into a young mussel.
However, about 10,000 young mussels still remained after this “selection”. They are about three millimeters in size and often drift into the sea for several hundred kilometers before settling with a size of about five centimeters in coastal areas.
Interesting fact: The reason mussels live in such large colonies is because males are much more likely to fertilize eggs. After the larvae float freely for about four weeks in the form of plankton, they attach to stones, piles, shells, hard sand and other shells.
Mussels have separate male and female individuals. Sea mussels are fertilized outside the body. Starting at the larval stage, they drift to six months before being able to settle on a hard surface. They are able to move slowly by gluing and detaching byss threads to achieve a better position.
Freshwater species reproduce sexually. The male releases sperm into the water, which enters the female through the current hole. After fertilization, the eggs reach the larval stage and temporarily parasitize on fish, holding on to the fins or gills. Before they go outside, they grow in the gills of a female, where oxygen-rich water constantly circulates around them.
Larvae survive only when they find the right owner - fish. As soon as the larvae attach, the fish body reacts by enveloping them with the cells that form the cyst, so they remain for two to five weeks. Growing up, they are freed from the owner, sinking to the bottom to start an independent life.
Natural enemies of mussels
Photo: What does a mussel look like?
Mussels are most often found in large clusters, where they are somewhat protected from predation due to their quantity. Their shell acts as a protective layer, although some species of predators can destroy it.
Among the natural predators of mussels there are starfish that are waiting to open the mussel shells and then swallow it. Numerous vertebrates eat mussels such as walruses, fish, herring gulls and ducks.
They can be caught only by people, not only for consumption, they are also for the manufacture of fertilizers, they serve as bait for fishing, food for aquarium fish and from time to time for the attachment of pebble shores, as in the English county of Lancashire. Mild winters complicate the situation, because then there are almost always many predators of young mussels.
The most famous mussel predators include:
- flounders (Pleuronectiformes);
- snipe (Scolopacidae);
- seagulls (Larus);
- crows (Corvus);
- scarlet scarlet (N. lapillus);
- starfish (A. rubens);
- green sea urchins (S. droebachiensis).
Some predators wait for the mussel to be forced to open its valves to breathe. The predator then pushes the mussel siphon into the crevice and opens the mussel so that it can be eaten. Freshwater mussels are eaten by raccoons, otters, ducks, baboons and geese.
Population and species status
Photo: Mussels in Russia
Mussels are quite common in many coastal areas, so they are not included in any Red List for conservation and have not received any special status. In 2005, China caught 40% of the world's mussels. In Europe, Spain has been an industry leader.
In the United States, mussel breeding events are being held and blue mussels are most often grown. Some mussels are the main edible clams. These include, in particular, species found in the Atlantic, North Sea, Baltic and Mediterranean.
Since the thirteenth century they have been bred in France on wooden boards. Mussels have been known since the colonization of the Celts. Today they are also grown on the Dutch, German and Italian coasts. Each year, about 550,000 tons of mussels are sold in Europe, about 250,000 tons belong to the species Mytilus galloprovincialis. A common cooking option is Rhine-style clams. In Belgium and northern France, mussels are often served with french fries.
Mussel in the absence of sanitary checks, it can in rare cases lead to poisoning if animals have consumed plankton that is toxic to humans. Some people are also allergic to their protein, so their body responds with symptoms of intoxication to the consumption of such specimens. Before cooking, the mussels must remain alive, so they are kept with the shutters closed. If you leave the hole open, discard the product.