The distribution range of mussels is unlimited. The Arctic Ocean, the Pacific and Atlantic coasts, the Black and Azov seas, the Hudson Bay, Greenland - this is only a small part of the water areas of their habitat.
Very interesting marine creatures are mussels. The structure of their shells is distinguished by a number of characteristic features determined by their habitat.
Mussel habitat
In shallow water in salty sea water, mussels are attached to underwater reefs, breakwaters, stones with byssus threads. The shell structure, great strength, as well as streamlined shape provide an excellent opportunity for their living in the surf zone with a fast current.
The life expectancy of mussels living in different conditions is different. The Black Sea live for about 5 years, the north - 10. The true centenarians are Pacific mussels, living for three decades.
Mussels - absolutely unpretentious creatures:
- food for them are unicellular algae, phytoplankton, bacteria;
- food enters the body as a result of seawater filtration;
- on a small area form thousands of settlements - mussel banks;
- infancy of mussels passes among plankton, and when the eggs become larvae and grow over shells, they adhere to rocks, stones and any other hard surfaces.
Mussels: external structure
Mussels are bivalve mollusks. The light yellow or blue-black shell of an adult mollusk covering an elongated body has the shape of a wedge, as well as a smooth surface with thin lines of growth. The shape of the shell is determined by the type and subspecies of the mollusk.
The external structure of the mussel has distinctive features:
- symmetrical left and right wings are connected by muscle tissue and a flexible ligament;
- the valves close very tightly as a result of contraction of the adductor muscle and protect the body of the mollusk from any external influences;
- the top of the shell is closer to the front edge - this creates a recognizable appearance of the mussel;
- the outer surface of the shell has a calcareous composition and a dark color ;
- the inner part of the shell has a layer of nacre - hypostracum.
A grain of sand that has fallen into the space between the sash and the mantle is gradually enveloped in mother-of-pearl - this is how pearls are formed.
Mussels: internal structure
Mussel is a mollusk, the structure of which is as follows:
- The body is formed from the trunk and legs, deprived of motor function due to the sedentary lifestyle of the mollusk.
- The head is absent, and there are no digestive organs such as the salivary glands, jaws, and pharynx.
- The mouth is located at the base of the leg and connects to the short esophagus opening into the stomach.
- The glands secrete byssus - strong strands of protein origin, which are necessary for fixing at the bottom of the reservoir.
- The body is covered with a mantle, falling loose folds on the sides and fusing in the back. Siphons are formed here, i.e. the food and air tubes.
- The internal structure of the mussel determines the respiratory system and the nutrition system .
- Shellfish breathe using gills located under the mantle and acting as a filter that pumps up to 70 liters of sea water per day. There are many cilia on the gills; due to their work, water passes through the body, delivering nutritious microorganisms to the oral lobes.
- Inedible particles, as well as excrement, are excreted due to the outlet siphon of the mussel.
- The structure of the heart is represented by two atria and one ventricle, from which two aortas depart, which are divided into several arteries.
- The circulatory system is not closed.
- The nervous system is represented by nerve nodes that are linked to each other by nerve trunks.
- Tactile organs are represented by the oral lobes and the tactile cells located along the edge of the mantle, in lamellar gills and legs.
Mussels: use
Mussels are used in various areas of life. The structure of beautiful shells makes sea creatures almost indispensable in the manufacture of souvenirs and jewelry. The mother-of-pearl layer gives a special decorative effect to products.
At the same time, mussels are a real find for true connoisseurs of marine delicacies. Since childhood, coastal residents have been familiar with the special ritual of preparing mussels: they are harvested from the sea day, cleaned and boiled right on the beach. On an industrial scale, mollusks are caught by dredges, which rake everything from the bottom of the sea for subsequent sorting of the caught.
Mussels with a delicate delicate taste, can decorate any feast: they are fried, boiled, smoked, pickled and even eaten alive.