Empty ponds and water trenches filled with crayfish can be an excellent source of income for any family. Arthropods are known to be valued for their high-quality and healthy meat, which contains a large amount of protein. Dishes from them are served in many restaurants in the world, they prepare various salads, sauces, side dishes from crayfish meat and are served as the main dish. All this indicates that the homestead with crustaceans can do a good job and bring considerable profit, but this is possible only after 5 years of investment and labor. Despite this, after the first settlement of the pond, the fruits of work will please the owners for the next 10 years.
Starting work on self-growing crayfish in your own pond, you need to understand the varieties, biological processes, features and methods of growing both young and adult individuals. On the territory of our country there are several types of arthropods, which are not much different from each other. Crayfish belong to animals that breathe with gills and have 10 legs. The carapace is quite dense and coated with chitin. The most famous within Russia are wide-toed crayfish, the claws of which, in comparison with the others, differ in width and thickness. There are also long-toed (narrow-toed) and thick-toed crayfish.
Creating a favorable habitat for crayfish
Under natural conditions, crayfish prefer to stop in calm running water, located mainly on the shady banks of rivers, lakes and canals. Decapod animals settle in burrows formed under the roots of old trees and plants that are in the pond. Crayfish are very demanding in relation to the purity of water, therefore, even at the stage of planning the pond, care must be taken to ensure that the water changes as often as possible and is not exposed to severe pollution and flowering. Also, do not forget about oxygen saturation and water temperature (should be equal to 17-18 degrees Celsius), intended for the reproduction and breeding of crayfish at home. Starting the construction of a reservoir, you should purchase sandy soil or rocky soil, in which crustaceans like to settle down. River inhabitants that fill the pond get along well with trout, which is not their food competitor.
In addition to creating favorable conditions for normal life and reproduction, arthropods must be provided with a sufficient amount of food. Asking the question of what river crayfish eat, you can find a definite answer: everything in a row.
Being omnivorous creatures, they eat any food found on their way. Especially popular in their diet are plants growing along the banks of rivers and lakes and containing lime: reeds, reeds, hornwort, and so on. Crayfish also prefer protein, presented in vivo in the form of snails, small fish, worms, various insects and tadpoles. The creature's nutrition changes with his age. It goes from smaller and plant foods to larger and more animal foods.
Walking through the markets in search of what to feed the river cancer, you can purchase food. Today there are various compound feeds created with the aim of feeding the river inhabitants, bred at home. Often, such additives contain a high percentage of sprouted wheat and other cereal crops that fill the natural needs of crustaceans and do not pollute the water. The optimal ratio of healthy vitamins and minerals provides a complete and healthy complementary foods. The plant components that make up the feed help to resist various diseases found in cancers. In the process of organizing the diet, it is necessary to remember that river crayfish eat quite a bit, so it is better to underfet rather than overfeed. An excess of nutrients in the reservoir can lead to their decomposition, pollution and turbidity, as a result of which all inhabitants of the pond begin to die.
There are several ways to grow cancers in an artificial environment, which depend on the goals and possibilities of breeding. However, in any case, as mentioned above, not one option for growing arthropods can do without pure and mineralized water containing the required amount of oxygen. Breeding of crayfish begins with the process of buying or equipping a reservoir in which there is access to a continuous source of water, for example, an artesian well.
The temperature of the water in the reservoir in the summer should range from 15-20 degrees. On the territory there should be 2-3 tanks installed for the purpose of transplanting young animals from their large relatives, capable of devouring the younger generation. You can also purchase an artificial pond, which is presented on the market in a large assortment: pools, ponds and the like. The main task of the purchased facility is to ensure rapid water circulation, so its shape should be oblong, and the depth should not exceed 7 meters. Small pools and aquariums are mainly used for breeding and hatching larvae from eggs, after transplanting females into prepared containers. The material in which the crayfish will be kept must be harmless, so metal vessels should be replaced with plastic or organic glass.
DIY pond construction for crayfish
If it is not possible to purchase a ready-made pond, you can build an artificial one yourself. Building a pond for a creature such as crayfish at home is a rather time-consuming task. First you need to choose a place for construction, next to which there is a lake, river or pond. Otherwise, the cost of the artificial reservoir will increase significantly. An important role in the construction is played by the waterproof bottom, on which the entire future structure will depend. Special waterproof and waterproofing layers are usually placed at the bottom, protecting the pond from leakage. In the early years of breeding crayfish, it is recommended to use a purchased tank that is reliable and has a longer service life.
The benefits and harms of crayfish
Very few lovers of sea food know how much river crayfish have healthy vitamins and elements. The benefits of breeding a crab congener in a household territory are obvious, and since they live only in a clean environment, they can be consumed without any fear. In addition to the rapidly digestible protein, cancer meat also contains a large amount of calcium, iron, phosphorus and cobalt. A wide range of vitamins such as E, D, B, C, sulfur and folic acid are found in their meat. Nutritionists recommend eating crayfish while on a diet, as their meat is a fairly low-calorie product - only about 80 kcal is contained in 100 grams of the product. Doctors also advise including cancer meat in the diet if abnormalities occur in the kidneys, heart, and gastrointestinal tract. By eating cancers for some time, you can cleanse the liver and remove bile from the body. The large amount of iodine in them serves as a prophylaxis of the thyroid gland.
Speaking about contraindications, it should be mentioned that arthropods are forbidden to people who have individual intolerance. Also, allergies can cause seafood, and in particular crayfish. The benefits and harms of crayfish are not comparable concepts, since the amount of nutrients, vitamins and macronutrients in the creature’s meat far exceeds harm and any of its shortcomings.
Crayfish is the highest cancer, a decapod squad that brings together highly organized crayfish, as well as crab and shrimp. For all representatives of this detachment, the body consists of a constant number of segments: there are 4 head segments, 8 thoracic segments and 6 abdominal segments.
If you look at cancer, you can easily notice that its body is two parts: the cephalothorax (which is the fused head and chest segments, the fusion seam is clearly visible from the back) and the jointed abdomen ending with a wide tail. The cephalothorax is hidden under a solid shell of chitin - a polysaccharide, and in addition is coated with calcium carbonate, which increases its strength.
The carapace is the skeleton of a crustacean. It performs a protective function, the internal organs of the cancer are safely hidden under it, and the muscles of the arthropod are attached to it. On his head are two pairs of antennas or antennae, covered with bristles and having a very long length, so the name “antenna” is more suitable for this organ. They perform the function of smell and touch, therefore, crayfish without them anywhere. In addition, at their base are the organs of balance. The second pair of antennae is inferior in length to the first, and is needed only for touch.
On the front of the cephalothorax there is a sharp spike; black convex eyes are located on its sides in the recesses. They are located on long movable stems, so that their cancer can rotate in all directions. This helps the animal to view the space around it well. The eye has a complex facet structure, that is, it consists of a large number of small-sized eyes (up to 3 thousand).
Claws are attached to the chest - these are the forelimbs. With them, he defends himself from enemies, catches and holds the victim, and he also lets them in during the fertilization period of the female in order to detain her and turn her back. From this it becomes clear that romance in inter-sexual relations is alien to the crayfish.
For movement, the animal uses four pairs of long, walking legs. In addition, he has small legs that are located on the inner surface of the abdomen and are called abdominal. They perform a significant function, helping the cancers breathe. They arthropod representatives drive oxygenated water to the gills. They are covered with a thin shell and are located under the cephalothorax shield, the latter creating a cavity for them.
Crayfish have to constantly work with their legs and pump fresh water through the cavity. Cancer females still have a pair of miniature bifurcated legs on which she holds eggs with developing crustaceans.
The last pair of limbs is lamellar tailed legs. In a tandem with a thickened telson (this is the last segment of the abdomen), they play an important role in swimming, thanks to them, cancer has the ability to quickly make “legs” backwards. Frightened, the cancer instantly leaves the place of danger, making sharp vertical movements of the tail, raking it under itself.
The arthropod also has a no less complex structure. He has 3 pairs of jaws. Each of which has a specific task - one grinds food, the other two work as sorting stations. They sort food particles and transfer them into their mouths.
Sexual dimorphism, that is, the anatomical difference between the female and male individuals of the same species, is present in these arthropods, although it is not pronounced.
Female and male - who is in front of us?
The female cancer is significantly inferior in size to the male, it is more miniature and elegant in contrast to the male. The same can be said about the size of its claws - they are more modest in size. Her belly is noticeably wider than the first part of the body - the cephalothorax, whereas in the male it is already his. And also a distinctive feature is the condition of two pairs of abdominal legs. In the female half of the cancers, they are underdeveloped, in males they are well developed.
Their color depends on the habitat, the composition of the water. By color, the crayfish merge with the bottom of the reservoir, and "dissolve" among the stones and snags. Therefore, they are usually brown, brown with a greenish or bluish tint.
In length, they grow to 6-30 cm. But how much they live, there is still no exact answer to this question. Experts cannot decide on their life expectancy. Some believe that cancers live up to 10 years, while others give them a much longer life span, speaking of a 20-year life expectancy.
Some crayfish prefer fresh water, others need brackish water. Many representatives of these crustaceans live in crystal clear water. Therefore, if crayfish were found in a reservoir, then we can safely assume that everything is in order with the ecological situation in this place. But the narrow-toed species, which is less picky than its counterparts to pollution, sometimes populates waters of low quality, which misleads the person.
Cancers need a sufficient concentration of oxygen in water and lime. With oxygen starvation, they die, and with a lack of lime - their growth slows down. The bottom they prefer non-clay or with a small content.
It affects the water temperature, this is understandable - the warmer the water, the less dissolved oxygen it can hold, therefore, the gas concentration decreases.
They settle at a depth of 1.5–3 meters, near the coastline, where they dig their minks. Crayfish of the same species usually live in a reservoir, but exceptions are rare when representatives of different species coexist in the lake.
There are 4 types of crayfish:
- Endangered Species - Fat Cancer, its number is so small that today it is on the verge of extinction. They live in the adjacent territories of the Black, Caspian and Azov Sea in clean, brackish water. Do not withstand a sharp increase in water temperature. It should not rise above 22–26 ° C. In length, it grows up to 10 cm. His body is painted in brownish-green color. Claws are dull, slightly forked.
A characteristic feature of thick-clawed cancer is a sharp notch on the fixed part of the claw, which is limited by tubercles in the shape of a cone. Does not live in contaminated areas.
- Wide-toed view found in many clean, fresh water bodies in the European part of the country. They can be found in any running body of water, where the water in the summer months warms up to 22 ° C. In length, this olive-brown or brown with a bluish tint representative grows up to 20 cm. Its claws are short and wide. In reservoirs with dirty water can not be found. Recently, its population has been declining, is under protection.
- Narrow-toed cancer feels good in fresh and brackish water, lives in the areas of the Black and Caspian Sea, slow-flowing rivers, low-lying reservoirs. The length of his body reaches 16–18 cm, and thirty-centimeter specimens are also caught. Chitin shell is painted brown - from light to dark. Its claws are very elongated - narrow and long. It is more resistant to pollution, therefore, it can populate contaminated water bodies.
- American signal cancer spread in many reservoirs of Europe, displacing other species. It was introduced to European countries after a decrease in the population of local types of crayfish due to the "crustacean plague." If we talk about Russia, then its appearance was registered only in the Kaliningrad region.
In appearance, the "American" looks like a wide-toed representative of crustaceans. A distinctive feature is a white or blue-green spot, which is located on the joint of the claw. In length, it reaches 6–9 cm, although some individuals can grow up to 18 cm. Their color is brown with a red or blue tint. It is resistant to the plague of cancers - a mycotic disease, from which river cancers massively die, but is a carrier of infection.
Freshwater crayfish are omnivorous, their diet is diverse - it has both plants and animals. For most of the season, their menu is dominated by plant foods. From plants, it tastes like algae and stalks of water lilies, horsetail, pond, elodea, water buckwheat. In winter, they eat up fallen leaves.
But for normal development, they need food of animal origin. They like to eat snails, worms, plankton, larvae and water fleas. They do not disdain carrion, eating at the bottom of a reservoir of dead birds and animals, prey on sick fish, that is, in a way, they are orderlies of the aquatic ecosystem.
Crayfish do not kill their victim, do not inject them with poison to paralyze it. They, like real hunters, hatch in an ambush, and instantly capture a gaping victim with claws. Holding it tightly, they gradually bite off a small piece of it, so dinner at the crayfish stretches for a long time. Specialists, with a lack of food in the pond or overpopulation, observed cases of cannibalism in them.
After wintering, mating and molting, crayfish prefer food of animal origin, the rest of the time they feed on vegetation. Feeding aquarium and pond crayfish is described in this article.
Crayfish are usually active in the dark or at dawn, but in cloudy weather they also get out of their minks. These are hermits. Каждое членистоногое живёт в своей норке, которая выкопана по размеру своего обитателя. Это помогает избежать нашествия незваных гостей и проникновения в жилище своего сородича или врага.
Днём они проводят в своих убежищах всё время, закрывая входное отверстие клешнями. В момент опасности раки пятятся назад и углубляются внутрь норы, протяженность некоторых составляет до 1,5 метра. Going in search of food, they do not go far from their home, move slowly along the bottom, pushing their claws forward. If the prey is within reach, then they act with lightning speed. He has the same quick reaction in moments of danger.
In summer, cancer usually lives in shallow areas, and with the onset of cold weather goes to depth. Females hibernate separately from males, because at this time they hatched eggs and hide in minks. The male crayfish half "heaps", gathering together several dozen individuals, overwinter in pits or burrow into the silt.
Males are ready for breeding when they reach 3 years, puberty of the female is longer by 1 year. By this time, crayfish grow to 8 cm in length. Among adult males, males are always 2-3 times more females.
Mating occurs in the cold season and falls on October - November. Timing may shift due to weather or climatic conditions. The male can fertilize only 3-4 females. If in most fauna representatives this process usually occurs by mutual agreement, then in the case of arthropods, mating resembles an act of violence.
Already in September, males noticeably become very mobile and show aggression towards individuals swimming past them. The male, seeing a female nearby, begins to chase her and tries to grab her with claws. That is why crayfish are much larger than females, since she will easily throw off a feeble cavalier herself.
If the male managed to catch up with the female, then turning her on her back, he transfers his spermatophores to her abdomen. Such violent insemination sometimes ends with the death of the female, and fertilized eggs also die with her. On the other hand, the male spends a lot of energy chasing and practically does not eat during this period, often he catches the last female, he simply eats to strengthen his strength.
A fertilized female lays eggs after 2 weeks, which attaches to the abdominal legs. She has had a hard time all this time - she protects future offspring from enemies, provides eggs with oxygen, cleans them of silt, algae and mold. In this case, most of the masonry perishes, the female usually saves about 60 eggs. After 7 months in June-July, crustaceans peck out from the caviar, measuring only 2 mm in size and remain on the mother’s abdomen for 10-12 days. Then the crustaceans start free swimming, settling in the pond. At this point, they reach a length of 10 mm and weigh about 24 g.
As mentioned above, a durable chitinous shell reliably protects cancer from the sharp teeth of the enemy, but on the other hand, it inhibits its growth. However, nature has taken care of solving this problem, and it has the ability to periodically completely reset the old carapace. Not only the chitinous coating of cancer is updated, but also the upper layer of the retina of the eyes and gills, part of the digestive tract.
In young crustaceans, the carapace changes up to 7 times already in the first summer, the number of molts decreases with age, and the adult individual costs one molt per season. The carapace changes only in the summer, when the water in the lake or river warms up.
You should not think that this process of “rebirth” proceeds easily and quickly. It can last from several minutes to a day. Arthropod with great difficulty first releases the claws, then the rest of the legs. When molting, the limbs or antennae often break off, and the cancer lives without them for some time. Over time, the lost parts grow back, but have a different look. Therefore, often rakolovy catch animals with different claws in size, one of them may have an ugly or underdeveloped shape.
Under the old “skin”, a new soft cover has already been formed to molt until it hardens, and for this it takes about a month, sometimes more, the arthropod grows in length and is an ideal food for predatory fish and its larger relatives. And since he molts neither in the shelter, but in the open space, he needs to safely get to his place of residence, where he can sit up to 2 weeks without food, and wait until the cover is more or less keratinized.
Crayfish fishing and hunting
Crayfish are caught all year round, they refuse to hunt them during molting, because the taste of meat is deteriorating. But this rule applies in those regions where it is quite common.
In some areas where the arthropod population is on the verge of extinction, fishing is completely prohibited, for example, in the suburbs or only allowed for a certain period, as in the Kursk region. It is usually forbidden to catch crayfish during fertilization and gestation of females with eggs.
Going for a catch, you need to find out what size and how many cancers can be caught. If you catch smaller arthropods, you may face an administrative fine. The commercial size of the crayfish, each region sets its own, but usually it is 9-10 cm.
How to catch?
There are 5 main ways to catch crayfish:
- Hand fishing. This is the most primitive way. The crayfish hunter must observe silence, carefully moving along the river, and look under every stone, driftwood, fallen trunks. As soon as the cancer is detected, immediately grab it and pull it out.
- On the shoe. The method was invented for a long time, but it is less effective. An old shoe, it is better to take it in large size, is filled with bait and thrown to the bottom. It is checked from time to time.
- With scuba gear. Some cancers practice scuba diving. This method is quite rare, if not exotic.
- On a cancer rod. The cancer rod has a simple device. They attach a fishing line to a stick with a pointed end, which they stick into the ground, and a bait to its end. Fresh fish or a frog are used as bait. The bait is folded into a nylon stocking and a pinch of bloodworm is added. And to make the smell stronger, the fish should be “flattened out”. Clinging to the “victim” of cancer, this can be seen by moving the sticks, fishing line or feeling the tremors of the fishing rod, carefully pulled out. However, at any time, the catch may break.
- Using rakolovki. Shells have various designs of open or closed type and allow you to catch several pieces of crayfish at once. They are filled with bait and lowered to the bottom of the pond. Every 20 minutes they are picked up and checked, having pulled out the catch, the rakolovka is sent back to the bottom. It is more practical to use closed structures, since it is difficult for crayfish to climb out of them.
The last two ways are considered more athletic.
When to catch?
Crayfish are best caught in the fall, when the water gets cool and the day is shortened, therefore, the time for hunting increases, as they are caught in the dark or early at dawn. Flowing reservoirs with a clay or rocky bottom are chosen, on the banks of which reeds, cattail or reeds grow.
How and when to catch crayfish is described in this article.
The chemical composition of cancer
They catch cancer for the sake of tasty, healthy and tender meat. The lion's share in it falls on proteins - 82%, fats - 12%, and carbohydrates - 6%. In 100 g of edible part, only 76 kcal.
There are many different vitamins in meat: almost all representatives of group B, fat-soluble ones A and E, nicotinic and ascorbic acid. The mineral composition is also diverse - potassium, phosphorus, sodium, sulfur, calcium, magnesium, iodine and iron.
The benefit of cancer meat is due to the fact that the vitamins and minerals in it are balanced. Low calorie content and a lot of easily digestible protein makes it indispensable for dietary nutrition. And also experts advise it to be used by people with cardiovascular diseases and the liver, with disorders of the nervous system and blood circulation. However, cancers are strong allergens, in case of intolerance to the product they immediately refuse it.
The tender and nutritious meat of the crayfish could not leave the cook unattended. And although only 150 g of meat is obtained from 1 kg of crayfish, the number of delicious recipes with it is huge. They are added to salads and soups, stewed, boiled, baked with Parmesan cheese, simply fried in oil. The meat goes to garnishes with seafood, it is prepared from aspic.
The value of crayfish for the environment
The benefits of crayfish for the ecosystem cannot be noted. They do not allow carrion and organics to decompose at the bottom, thereby inhibiting the development of pathogenic microorganisms. On the other hand, some experts believe that eating fish caviar, they have a negative impact on the population of the latter, although this is not proven by facts and is more relevant to the assumptions.
Cancer of the river (kept in a terrarium)
Young cancer in the aquarium is very beneficial. He daily, or rather nightly, carefully examines the entire aquarium and collects all kinds of garbage.
Cancer is also a very funny animal. We will observe the cancer walking along the bottom of the aquarium. Despite the apparent clumsiness, he easily walks on his eight legs until he stumbles upon an obstacle. But on his way met a fish. Cancer pressed to the sand: all attention is on the fish, claws are wide open in a fighting position. But the fish is not going to offend cancer at all. She's just curious. She swims closer - the cancer recedes. Finally, he doesn’t stand it and starts off. The fish floats away and peace is restored.
What will happen if the fish is aggressive? In this case, our cancer will show extraordinary and at first glance incredible agility. Much faster than a fish of the same size would do, it will hide in the opposite side of the aquarium. It is impossible to keep track of the movements of his "tail" (in fact, this is the abdomen). Sharply reducing the "tail", the cancer swims, and how it swims! Nice to see. Try to catch it with your hand. You try to grab it from the front - the cancer immediately swims away, you approach it from behind - it sees it perfectly with its complex eyes, it instantly turns - and now it is gone. He swims "back to front," perhaps because he resorts to swimming only when retreating. In this position, the pursuer is clearly visible to him. You can catch cancer from the aquarium only by carefully placing the net.
Now let's observe the behavior of cancer during food collection. In this case, he uses for movement only two rear pairs of legs equipped with claws. He holds large claws horizontally in front of him, and the second and third pairs of legs equipped with small claws exhibit extraordinary mobility. Each stone found on the way is carefully examined, but not with the help of vision, since cancer must constantly be monitored for safety, but for touch. Every click is checked, not a single crease, not a single notch can escape a thorough check. Sometimes this or that leg with the agility of a balancer will send something to the mouth (the impression is that the mouth is located on the stomach). Sometimes a cancer spits something in disgust. Appendages located near the mouth are as if to ensure that not a single edible piece is lost. Cancer cleverly cuts the body of a dead snail, removing it from the shell in pieces. He does not pay attention to a live snail. He is not dangerous to fish either. Young black mollinesia even climbed into his shelter, which he dug under a stone. Two of them even slept there, and the cancer did not touch them. If a large fish comes to him, he will try to frighten her with menacingly opened claws, but he will never touch him.
I kept crayfish in the aquarium twice. The first time I selected several young centimeter crustaceans (the female carries them under her abdomen in the summer months). He planted one in a separate small vessel, and let the rest into a common aquarium. And in vain, since all the fish from the scalars to the guppies attacked them - and soon there was nothing left of the crustaceans - the fish only "licked". The very first crustacean, which I fed with dried barley, soon reached a length of two centimeters, and I transplanted it into a common aquarium, separating it with a net for safety. He felt good there and a year later grew to seven centimeters. Then I let him out into the river.
Another time, a six-centimeter long crustacean was planted in the aquarium. But I was not lucky with him. He was free to get used to more space, and from time to time to deal with my plants. So he cut the Marsilia, which I hardly got and planted in the middle of the aquarium. Another time, making an emergency exit from his hole, he got to the roots and calmly cut them. I was forced to get rid of him. Now he lives in a large aquarium with cichlids at a permanent exhibition. There are no plants in this aquarium and the bottom is rocky.
In conclusion, I want to give advice to those who want to acclimatize cancer at home.
1. The smaller the crustacean, the easier it gets used to new conditions. Accustomed to the aquarium, it will not cause you much trouble.
2. Crayfish from cold mountain and forest streams do not get used to stagnant water. Easier to adapt to river or even better - pond cancer.
3. Place the cancer (I recall, it is better than a small one) in a small vessel (a two-liter jar) and create a flowing condition for it for one to two days with a small stream of water. On the third day, stop the water, but replace it with fresh water three to four times during the day. On the fourth day, change the water once, but the jar should be kept in a cool place. On the fifth day, change the water again, and put the jar near the aquarium. After temperature equalization, that is, on the sixth day, you can put our crustacean in the aquarium prepared for it.
We must remember that the cancer must dig a mink for itself. To do this, put a suitable stone in a place that suits you, and a little rake sand from under it. Put the crustacean in the formed recess, and then he will complete the matter. If, nevertheless, he begins to dig somewhere else, stop him, level this place. In the end, you make him submit to your will.
Breeding crayfish is widely practiced worldwide. Each country has its own technology for growing arthropods, but they all follow the rules:
- bottom of reservoirs with a small amount of sludge,
- the presence of pure fresh water rich in oxygen is necessary,
- compliance with the temperature regime,
- compliance with the composition of water.
One of the most economical breeding methods is considered pond. It consists in arranging several ponds (usually in the amount of 3-4 pieces), in which crustaceans are grown.
With a great desire, crayfish can be grown at home - in the aquarium. The main thing is to find females with caviar, which is attached to their abdomen. They are released into the water and eggs are incubated, it is necessary to monitor the water circulation and aeration of the water.
It is worth taking care of the feed base in advance. Crustaceans are fed when the water is heated above 7 ° C by boiled or fresh food, placing it on special trays.
Small crustaceans, which were shed for the second time, are moved to the mother pond, and then sent to a new one or left in the same pond, provided that it is suitable for their wintering. The crayfish, which turned one year old, are released into the feeding pond, here it is necessary to reduce the density of planting. They reach marketable size in the 2nd or 3rd year.
In the natural environment, due to environmental degradation, general pollution of water bodies and unlimited fishing, their numbers are declining annually. From crayfish on the verge of extinction there is a thick-toed species, and the population of the broad-toed species also "aspires" to this. They are listed in the Red Book, and fishing on them is strictly prohibited.
There are several interesting facts about crayfish that you should know:
- crayfish have blue blood
- in the true Olivier salad recipe, one of the ingredients was boiled crayfish, in the amount of 25 pieces,
- crayfish are forbidden to eat by Jews, as they are considered “non-kosher” food,
- during cooking, all the pigments that are responsible for the color of the cancer decay, except for carotenoids, which is why after heat treatment it turns red,
- Previously, it was believed that these arthropods are insensitive to pain, experts have proved that this is not true, by cooking living crayfish people doom them to a painful death,
- the largest crayfish are caught on the island of Tasmania, its length is 60 cm.
In conclusion, it is worth noting that the meat of crayfish is rich in trace elements that have a beneficial effect on the human body as a whole. However, it is not only healthy, but also delicious. That is why crayfish is one of the most popular representatives of arthropods.