Natalya Bernazh-Gorbenko
One day while walking we found a little shell with a hole. Naturally we had questions:
What is it for? hole?
How many years shell?
This is an adult shell or baby shell?
Who lived in this shell?
-Hole Was it always there or did it appear later? and why?
First we remembered what we know about shells. It turned out not so much.
From the book we learned that mollusks live in such shells. A shells They are called bivalves because they consist of two parts - valves, and live both in the sea and in salty sea water.
We also learned that age shells can be recognized by stripes-lumpy growths around the circumference of the shell. How many stripes, so many years. Let's do the math.
But what is it for? hole in the sink? This question gives us no rest.
We put forward our hypotheses.
Marika and Lera's version: -Need a hole to breathe.
Marika spent time with her mother study and told us a lot of interesting things. Having examined the structure of the mollusk, she found out. THAT THE MOLLUSK BREATHES OXYGEN contained in water. For breathing and feeding, there are special siphon openings at the shell; it is through them that the mollusk sucks in water. This is how he eats and breathes. Marika's hypothesis that hole is needed for breathing. not confirmed.
Matvey's conjecture: The hole was made by a fish - a needle.
Matvey was given a task: together with your mother, read about the needle fish and tell us about it and test your hypothesis.
Matvey told us a lot of interesting things about needle fish. It turns out that she doesn’t eat shellfish at all. and by small crustaceans - plankton. We also learned that the needle fish is a close relative seahorse. And the needle-like growth is soft and incapable of digging through a thick and strong shell. Matvey’s version was also not confirmed. We decided to do it ourselves hole in the sink.
Matvey was the first to complete the task. hole he did it with a screwdriver and dad. Roma did hole using a sharp screw yourself!
And Lisa decided that hole can be burned off with acid. With the help of her mother, she carried out her experiment. Unfortunately, the hole didn't appear.
Now we know that hole someone is drilling. But who?
Lisa, Matvey, Marika and Roma on different paths learned: he makes the hole who really wants to eat tender shellfish meat. We learned that the mollusk has enemies - starfish and rapana - predatory mollusks.
Lisa went on an excursion to the aquarium. She learned that starfish don't hole in the sink. she opens the shell doors with her rays.
On the Internet we found articles about rapana. This is the largest snail, one of the most ferocious predators! Young rapana drill holes in the shells of bivalves with their tongue-drill, and adults open their shells with a muscular leg and eat the opened mollusks.
We also learned that the Rapanas moved from Sea of Japan to Chernoe. Now in the Black Sea, due to rapana, there are almost 2 times fewer mollusks than 40-50 years ago. Rapana have proliferated greatly due to the fact that their main enemies, starfish, are absent in the Black Sea due to low salinity. Sea stars They eat rapan in their homeland, the Pacific Ocean. So that's who does it holes in the shell!
In different places around the world, fishermen use some parts of local plants, roots, leaves, juice, to poison or stupefy fish so that they float to the surface where they can then be easily collected. For the same purpose, in extreme situations, you can use bivalve shells or mollusks.
Most plants suitable for poisoning fish in water bodies grow in southern and tropical climatic and geographical zones. For example:
— Derris bush and Barringtonia tree — from South-East Asia to Australia.
— Desert Rose — Africa and the Arabian Peninsula.
- Juice of the Assaku bush, shoots of many types of Timbo and Lonchocarpus lianas, roots of the Brabasco tree - in South America.
— Poultry grass and Virginian goat's rue — North America.
On the territory of the CIS countries there is only one plant suitable for such purposes - Djungarian mullein, which grows in the mountains Central Asia at altitudes up to 2600 meters. Therefore, the likelihood that if you find yourself in a situation you will find, identify and be able to use one of the above-mentioned plants is negligible.
A more realistic way only in a truly hopeless extreme situation!, poison the fish, and then collect it, use it for food, do this using ordinary bivalve shells and other mollusks, or rather their shells. In addition, shell meat itself is suitable for use as food or bait for fishing. However, we will present everything in order.
Bivalve shells as food in extreme situations.
Almost all bivalve mollusks of fresh and slightly salty waters, that is, rivers, streams, swamps, lakes and seas, are considered edible - such as, for example:
— Toothless from 8 to 20 cm long. They are found at the bottom of standing and slowly flowing reservoirs with silty soil.
— Perlovitsy from 5 to 10 cm long. They live mainly in flowing water, in reservoirs with sandy soil.
— Sharovka 2 to 3 cm long. They can be found in the sand and silt of various bodies of water, almost round in appearance and yellowish or yellow-brown in color.
Preference for eating should be given to pearl barley, which is easy to spot by the paths it leaves as it moves along the bottom. At the end of such a path, a prominent tubercle is usually visible - there is a mollusk buried in the ground. Or sometimes it’s enough just to feel the bottom with your bare foot and find a hard ribbed surface, these will be pearl barley shells. In favorable conditions, you can collect more than a bucket of them in 10-15 minutes. When searching for and collecting shells, you should be careful - the shell valves are very sharp and can easily injure.
Recipe bivalve shells.
Bivalve shells are prepared in a very simple recipe. We lay them out as close to the fire as possible with the slit facing up; after a while the shells will open. In the opened shell we find a scallop - this is the edible part of the shell, cut it off and fry it over the fire. If you have a cauldron, then after washing the shells, you can boil them in the shells and after the shells open, cut out all the meat and eat.
Or first cut the constipation muscles by inserting a knife through the gap between the valves, and then cook. Even pearled pearls caught in clean, spring water can smell strongly of mud. If there is salt, for a more pleasant taste, the shell meat should be salted during cooking.
Bivalve shells as bait for fishing.
The pearl barley shell is perfect for catching tench, bream, carp, catfish, large crucian carp and many other fish. We open the shell using one of the methods described above, use a knife to separate the meat from the shells and place it on the hook.
Bivalve shells as a poison for fishing.
The shells of mollusks partly consist of a special nitrogenous, chitin-like substance - conchiolin, usually impregnated with lime. It is this lime that can be used to poison fish, but first it must be extracted from the shells themselves. To do this you need:
1. Collect shells in an amount equal to the volume of 4-5 buckets.
2. Open the shells and clean them of entrails, which can be used as bait or for food (see text above).
3. Break the peeled bivalve shells and grind them between stones, the finer the better, almost to a powder.
4. Mix the resulting powder with charcoal in a 1:1 ratio.
5. Burn the resulting mixture over a strong fire until it begins to turn brown and then turn white.
6. When the mixture begins to turn white, remove from heat.
7. Throw the resulting lime into the water and wait until the fish floats up.
A few important notes on using bivalve shells as fish poison.
The method described above for obtaining fish by poisoning it is poaching, therefore it is permissible only in extreme situations that threaten health and life!
— Fish poisoned with such lime is safe for human consumption.
— The method is quite effective only in any stagnant or weak-flowing water.
“If this method is used in closed reservoirs, then you can destroy all the fish there, thus depriving yourself of a source of food for the future and causing harm to the environment.
“However, if you poison fish in a natural or artificially created coastal backwater, then soon the usual number of fish in it will be restored.
How are shells formed?
- How are shells formed?
If you've ever walked along the beach, you've probably seen seashells lying on the sand where they were thrown out by the waves. Such shells are almost always empty; they are the former home of some dead sea animals.
By the way, shells are found in wooded areas, rivers, and ponds. When people talk about shells, they usually mean the soft-bodied animals known as molluscs.
Most mollusks have a shell that protects their soft body. A shell is the skeleton of a mollusk. It is a part of the animal, and the mollusk is attached to it by muscles. The soft shellfish inside never leaves its home.
The shell is made of limestone by the mollusk itself. Certain glands can take limestone from the water and deposit tiny particles at the edges or along the inside of the shell. As the mollusk grows inside, the shell also increases in size. You can see the growth lines, which are marked by ridges (bulges) running parallel to the outer edge of the shell. You've probably noticed these growth lines on oyster shells. The appearance of other scars is caused by scars on the mollusk's mantle or the muscles of its body.
The shell of a mollusk consists of three layers. The outer one is covered with a layer of horny substance, which does not contain lime. Underneath is a layer of calcium carbonate. The inner layer is the mother of pearls, or nacre. It consists of a very thin layer of calcium carbonate and horny substance.
The color of the shell depends on the color of the substance secreted by some glands of the mollusk. Therefore, the shell can be speckled, plain or painted with stripes and lines. Some shells are so tiny that they can only be seen through a magnifying glass, while a giant sea clam can be up to a meter long. - A shell is both an external skeleton and a house that bivalves and gastropods - and all other mollusks, except for some special groups - such as nudibranchs or octopuses build for themselves. As the mollusk grows, the shell also grows.
The shell, layer by layer, is composed of special cells at the edge of the mantle, capable of forming limestone crystals from salts sea water. In winter, mollusks grow more slowly, and in summer - faster; therefore, seams and convex growth rings remain on the shell (not to be confused with the normal concentric sculpture of a shell, for example in the Venus) - from them you can calculate the age of the mollusk - like from the annual rings on a tree cut.
Most bivalves live on a sandy or muddy bottom, burying themselves entirely in it, and putting out siphons - two tubes through which they suck in and release water. From this water they take both oxygen for breathing and food - microscopic plankton and detritus.
All mollusks know how to make pearls: when, for example, a grain of sand accidentally appears between the shell and the mantle, the mollusk begins to fight the foreign body - the cells of the mantle envelop it with layers of nacre - the same with which they line the inner surface of the shell - a pearl is obtained. Mother-of-pearl is thin plates of limestone, light is refracted and scatters in them into multi-colored rays - so it seems to us that mother-of-pearl has color. Only a few species of bivalves can make precious pearls, and, for example, those of the Black Sea mussel - they look more like large gray grains of sand.
Structure of a bivalve mollusk - Bivalvia
Only a few bivalves live on a solid surface: the mussel Mytilus galloprovincialis and the mytilaster lineatus use a bundle of strong threads - a byssus - to attach to stones and algae stems, and oysters grow to the stone and to each other with their shells. During life, the shells of the oyster Ostrea edulis were white-green-pink, but now we are finding more and more black shells, because they lay for a long time in the ground, where everything turns black from hydrogen sulfide. The stone borer Pholas dactylus drills burrows in rocks with a drill shell.
Venus gallina shells:
on the right - normal color,
black - lay buried in the ground and darkened from hydrogen sulfide, yellow - were thrown back to the surface of the bottom;
white - worn out by sand.
Most of the shells on the beach are donax shells and conch shells - these are the most common mollusks of the sandy shallow waters of the Black Sea, there are a lot of cocked hats Spisula triangula. Everywhere on sandy beaches Black Sea - tiny firefly shells - lucinella and lentidium. More and more weighty shells of Scapharca inaequivalis - this tropical bivalve entered the Black Sea less than 20 years ago.
SINK
the hard coverings of the body of some animals, such as snails, bivalves or barnacles. Of greatest interest, especially from the point of view practical use and collecting, represent calcareous shells of mollusks. To protect your soft vulnerable body from natural enemies mollusks secrete a substance consisting mainly of calcium carbonate and hardens into a material similar in density to marble. They acquired this ability in the early periods of the geological history of the Earth, already by the beginning of the Cambrian (570 million years ago). Rocks of this age contain many of their fossilized shells.
MOLLUSK SHELLS. (Left to right) Busycon contrarium, Aequipecten gibbus, Littorina littorea
Types of shells. There are five main classes of mollusks: bivalves, gastropods, testapods, spadepods and cephalopods. Representatives of each of them have their own characteristic type of shell.
Bivalve. Bivalve shells consist of two halves (valves), connected to each other by an elastic ligament and held in a certain position by interlocking teeth. The hinge line - the side on which the valves are connected - is considered upper, or dorsal (dorsal), and the opposite - where they can diverge - is considered lower, or ventral (ventral). In some species the valves are identical, while in others they differ slightly in size, shape and color. Oysters, clams, mussels and scallops are all part of the bivalves group.
Gastropods. The shells of gastropods, unlike bivalves, are solid, i.e. not divided into flaps. Members of this group, often called snails, can be found on land, in fresh water and in the sea. Usually their shells are twisted clockwise around central axis(column) like a spiral staircase. If you hold such a shell, called right-handed, with the sharp end (top) up, then its “entrance” hole - the mouth - will be on the right. If the mouth is on the left, the shell is called left-handed. At the mouth, there are inner and outer lips, and its lower edge usually bears a projection (anterior canal), which can resemble either a long tube or the curved spout of a teapot. If there are two canals, the second, located in the upper part of the outer lip, is called posterior. Gastropods move with the help of a muscular outgrowth - the leg. When the animal senses danger, it withdraws its leg into the shell; the mouth is closed by an operculum - a small hard formation attached to the back of the leg. The lids different types vary in structure, size and shape (according to the opening being closed) and may resemble a thin disk, button or marble plate. Each whorl of the shell is called a whorl, and the last and largest is called the trunk whorl. They can be clearly visible, for example in trumpeters, flattened and almost fused in appearance, like cones, or not noticeable at all from the outside, like in cypras.
Armored. The shells of these mollusks consist of eight overlapping dorsal plates. These animals are also called chitons, since from below, from under the shell, a leathery belt protrudes, reminiscent of the edge of ancient Greek clothing - a chiton. Shellfish usually stay under rocks and in crevices; they are difficult to tear off from the substrate, to which they are firmly attached by the sole of a muscular leg.
Spadefoot. The shells of these mollusks are slightly curved tubes, reminiscent of elephant tusks in shape. Their length ranges from 2.5 to 12.5 cm; some are white and matte, like chalk, others shine like porcelain.
Cephalopods. Cephalopods may be the most interesting of mollusks from an evolutionary point of view. Judging by the fossil remains, they once had shells up to 4.6 m long. Most modern cephalopods have only small internal shell vestiges. Squids, cuttlefish, and octopuses belonging to this class are now protected by their powerful tentacles, camouflage coloring and “ink” curtains released into the water. The only living cephalopods with an external shell are members of the genus Nautilus. The decoration of any collection is the species Nautilus pompilius. Its spiral, iridescent mother-of-pearl shell is composed of a series of chambers and forms a perfect logarithmic spiral; the width of the whorl increases, maintaining a constant ratio to its length. As the body grows, it builds new chambers and moves to live in the last, largest of them.
Shell composition and growth. As clams grow, they secrete a substance that increases the size and thickness of their shells. This secretion, secreted by the fold of skin surrounding the body, called the mantle, consists of calcium carbonate mixed with phosphate and magnesium carbonate. In bivalves, the mantle covers the body from the sides, and in gastropods it forms the fleshy lining of the mouth. The growth lines on bivalves shells run parallel to their outer edge, and in gastropods new whorls are added to the shells. There are three layers in a mollusk shell. The outer (periostracum) is rough and consists of the organic substance conchiolin; the middle, or porcelain-shaped (ostracum), is formed by small prisms of calcite or aragonite, and the inner (hypostracum) is formed by parallel plates of aragonite and is often mother-of-pearl. The pearlescent iridescent shine is due to translucent layers of calcium carbonate. The shapes of shells and the color of their outer surface are extremely varied. Some are no larger than the head of a pin; they are so small that the beauty of their shape cannot be fully appreciated without a magnifying glass. Others, for example, the giant tridacna (Tridacna gigas) from the Indian and Pacific oceans, reach a diameter of 60-120 cm and a weight of 135-180 kg. They gave rise to legends about divers who fell underwater into a trap made from the closed shells of this mollusk.
Spreading. Modern ranges of approximately 50,000 species sea mollusks depend on the temperature and salinity of the water, as well as the outlines of the primordial oceans. Probably the richest source of shells in the world is a wide belt extending from warm waters East Africa through the Indian Ocean to Australia and the southern islands Pacific Ocean. Many of their best specimens (cyprias, cones, terebras, venerids) are mined here - off the African coast between Kenya and Mozambique, in the waters off Queensland (Australia) and the tropical seas surrounding some islands of Indonesia, the Philippines and the Ryukyu Archipelago. The second most important is the West Indies region, stretching from Bermuda through the Antilles to Brazil. This area abounds in the shells of molluscs such as Triton's horn, Strombus, Cassis and Fasciolaria. There are several other places in the world where interesting specimens of shell mollusks are found. Since the temperature in the Mediterranean Sea is approximately the same as in the Caribbean, many species of scallops, whelks, fasciolaria and needleworts are found in both these areas. Along the east coast of the United States you can collect beautiful naticids, cones, anomia and olives, left-handed busicones, as well as strombus and graceful angel's wing bivalves. Two small islands located off the west coast of Florida, Sanibel and Captiva, are considered the best places collection of shells in the USA. Off the west coast of the country there are many fairly common species, as well as the rarer abalone and sea cuttings. There are approximately 50,000 known taxa of freshwater mollusks, primarily classified as bivalves and gastropods. They live not only in rivers and lakes, but also in hot springs, caves, at the base of waterfalls, and even in frozen ponds in polar regions. Most land mollusks are pulmonate gastropods - snails with a special respiratory apparatus. Their shells are often as brightly colored as those of the most colorful marine species. These snails live among moist vegetation, mainly in trees; one of their most famous types is grape snail(Helix aspersa) is considered a delicacy in France.
Usage. The history of shell use goes back over 10,000 years. Red cassis from the South Pacific are found in prehistoric Cro-Magnon caves in Europe. Their presence thousands of kilometers from their homeland suggests that they served as money, which means that trade between these widely separated areas inexplicably existed already in the early stages of human history. Primitive, undoubtedly used shells as decorations. Shells with sharp edges, such as some common bivalve shells, were used as cutting tools. Particularly interesting is the role of shells as currency. In the past, such “money” was widespread in America, Asia, Africa and Australia. The most valued in this sense was the cypraea moneta, or cowrie. Even today on some islands of the Pacific and Indian Oceans The shells of another cowrie species, C. annulus, are used as money. Among the peoples of Central Africa, the possession of bundles of large cowries served as evidence of personal or tribal wealth, and in West Africa these shells were used as payment until the mid-19th century. In some areas of the African continent, for example in the territory of present-day Angola, coins made from the cut shells of the land snail Achatina monetaria were common. On the islands north of New Guinea, shells were also often ground to a suitable size for use as currency of various denominations. Until 1882, trade in the Solomon Islands was carried out using such “coins” of a standard shape and a certain size. Shell money laid the foundation of the economy North American Indians. The shells of spadefoot animals (for example, the sea tooth - Dentalium pretiosum) were used as coins long before the emergence of the Hudson's Bay Company. A string of 25 of these large shells was enough to buy a canoe. A remarkable achievement of the “coining” of the American aborigines was the so-called. wampum. It consisted of polished cylindrical pieces of whelk shells, Mercenaria mercenaria and Littorina littorea, strung on leather straps. Typically, this money was made in coastal areas, where the highly prized purple mercenaria shells and giant white whelks were more readily available. From here the ready money was transported deep into the country. Shells have been used for other purposes for centuries. Collections discovered in Roman dwellings indicate that they were collected already in ancient times. Medieval pilgrims wore the St. James comb (Pecten jacobeus) on their hats as a sign that they had crossed the sea and reached the Holy Land. Large shells of cyprians, whelks and other mollusks were often depicted by Renaissance artists. A famous example serves as a huge comb in Botticelli's painting The Birth of Venus.
LITERATURE
Burukovsky R. What the shells sing about. Kaliningrad, 1977
Collier's Encyclopedia. - Open Society. 2000 .
See what “SINKS” are in other dictionaries:
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