The distribution area of mussels is unlimited. The Arctic Ocean, the Pacific and Atlantic coasts, the Black and Azov Seas, the Hudson Bay, Greenland are just a small part of their habitats.
Very interesting sea creatures - mussels. The structure of their shells differs in a number of characteristic features due to their habitat.
Mussel habitat
In shallow water in s alty sea water, mussels are attached to underwater reefs, breakwaters, stones with the help of byssus threads. The structure of the shells, their great strength, as well as their streamlined shape, provide an excellent opportunity for their habitat in the surf zone with a fast current.
The life expectancy of mussels living in different conditions is different. The Black Sea mussels live for about 5 years, the northern ones - 10. The real centenarians are the Pacific mussels, living for three decades.
Mussels are absolutely unpretentious creatures:
- they feed on unicellular algae, phytoplankton, bacteria;
- food enters the body as a result of seawater filtration;
- on a small area they form settlements of many thousands - musselsbanks;
- Infancy mussels pass among the plankton, and when the eggs become larvae and overgrown with shells, they stick to rocks, stones and any other hard surfaces.
Mussels: external structure
Mussels are bivalves. The light yellow or bluish-black shell of an adult mollusk, covering an elongated body, has the shape of a wedge, as well as a smooth surface with thin growth lines. 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 flaps attached by muscular tissue and flexible ligament;
- the valves close very tightly as a result of the contraction of the adductor muscle and protect the body of the mollusk from any external influence;
- the top of the shell is closer to the front edge - this creates a recognizable appearance of a mussel;
- outer surface of the shell has a calcareous composition and a dark color;
- the inside of the shell has a layer of mother-of-pearl - 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 whose structure is as follows:
- The body is formed from a torso and a leg, devoid of motor function due to the sedentary lifestyle of a mollusk.
- The head is missing, there are no such digestive organs assalivary glands, jaws, pharynx.
- The mouth is at the base of the leg and connects to a short esophagus that opens into the stomach.
- Glands secrete byssus - strong threads of protein origin, which are necessary for fixing at the bottom of the reservoir.
- The body is covered with a mantle, falling in loose folds on the sides and growing together in the back. Siphons are formed here, that is, food and air tubes.
- The internal structure of the mussel determines the respiratory and nutritional systems.
- Mollusks breathe with the help of 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 nutrient microorganisms to the oral lobes.
- Inedible particles as well as excrement are expelled thanks to the mussel's excretory siphon.
- The structure of the heart is represented by two atria and one ventricle, from which two aortas depart, dividing into several arteries.
- The circulatory system is not closed.
- The nervous system is represented by nerve ganglions that interlock with each other by nerve trunks.
- Tactile organs are represented by oral lobes and tactile cells located along the edge of the mantle, in lamellar gills and a leg.
Mussels: Uses
Mussels are used in various areas of life. The structure of beautiful shells makes sea creatures almost indispensable in the manufacture of souvenirs andjewelry. 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 sea delicacies. Residents of the sea coasts have been familiar with the special ritual of cooking mussels since childhood: they are collected from the sea day, cleaned and boiled right on the shore. On an industrial scale, molluscs 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, marinated and even eaten alive.
