Kamchatka crabs are one of those inhabitants of our planet that have long become an object of close attention, both from the planet’s leading specialists and from ordinary fauna lovers. And this is perhaps not surprising. The animal is actually unusual and quite rare today.
Unfortunately, there are still those representatives of the human race for whom Kamchatka crabs are just one of the lines on the menu of an expensive restaurant.
We are not at all trying to preach or promote vegetarianism. To eat or not to eat animals is, undoubtedly, everyone’s business. However, after reading the proposed sections, the reader, if desired, will be able to reconsider his views on the surrounding reality, for example, by learning what characteristic features the living Kamchatka crab has, where it lives, what it eats and how it reproduces.
Section 1. Where do these animals live?
Basically, the name speaks for itself. Even the most incurious reader will immediately realize that this type of crab is found en masse in Russia, namely off the coast of Kamchatka.
Although not everyone knows that it is also found in Primorye. Among other things, it can be found in the territory from Posiet Bay to the Pacific coast of Canada, if you move through the northern part of the Japanese Sea to the Okhotsk and Bering Seas along the Aleutian Islands.
Section 2. What does it look like?
The Kamchatka crab (in Moscow, St. Petersburg and other cities of central Russia it can only be seen in the zoo) is a fairly large species of crustacean.
By the way, it is not uncommon for him to be mistakenly classified as an ordinary representative of this species. This is nothing more than an unfortunate misconception. Why? The thing is that it has one significant difference: instead of five, this creature has four pairs of legs, so it would be more correct to classify it as a craboid.
The shell and phalanges of the Kamchatka crab are brown, have purple spots on the sides, and the abdomen is yellow-white.
The Kamchatka crab can live 20 years. Surprisingly, in rare cases, in an adult, the carapace grows up to 20-25 cm in width, and the weight can reach 7 kg. On average, there are males with a shell of 15-16 cm and a weight of 2.5 kg.
The females of this crustacean are much smaller in size and weight. They are distinguished by semicircular shapes and a fairly wide abdomen, under which eggs develop almost all year round. But the abdomen of males more closely resembles a symmetrical triangle.
Section 3. What do they eat?
Kamchatka crabs are real predators. They feed on mollusks, polychaetes, echinoderms, small sea acorns and many other bottom animals.
The claws of the Kamchatka crab are quite powerful. With them, he effortlessly tears apart the prey, then, using his legs and jaws, grinds it and sends the food into his mouth.
As a rule, the right claw is larger in size; it is used to break mollusk shells and crush the skeletons of sea urchins, but the left one is used by the crab only for gripping.
Section 4. Where do they winter?
Perhaps the answer to this question cannot but interest me. But in fact, where does the animal spend time during the cold season?
The wintering grounds of crabs are located relatively far from the coast, where the depth reaches 110-200 meters. Kamchatka crabs do not hibernate; they lead exactly the same active lifestyle in winter as in summer.
They have to go deeper due to the lower water temperature in shallow water and the formation of ice. In the spring, as soon as the sea bays are cleared of ice, crustaceans begin to move to smaller areas. It is interesting to note that during this period, male and female king crabs move towards the shore in separate groups. This can be explained simply: female crabs carry last year’s developed eggs on their abdominal legs. Halfway through the adults' journey to the shore, the larvae hatch.
Section 5. How do Kamchatka crabs reproduce?
About a month after migration, shoals of female and male individuals mix in shallow water, and the mating period begins. Moreover, female Kamchatka crabs at this time look far from beautiful: a dirty shell overgrown with shells, empty shells from eggs completely covering the abdominal legs. But the males do not pay attention to this, they choose their girlfriends, pinching the females’ claws with their claws. Couples remain in this “handshake” position for 3 to 7 days.
After this, the males help the females molt - they pull off the females' contaminated old shell, and then attach spermatophores to the bases of their third pair of walking legs.
It should be noted that after mating, females and males again migrate separately, going in search of food.
Before the summer migration, males also molt, but alone among the stones. After a while, the female lays eggs, fertilizing them from the spermatophore. The female carries the eggs on herself until next spring.
Section 6. Why is this type of animal valuable?
Kamchatka crabs, or rather, their tender meat, are highly valued by gourmets for their excellent taste, minimal amount of calories, high content of mineral elements, zinc, iodine, vitamins, and amino acids.
The most valuable are caviar and meat located in the area of the legs, claws and the articulation of the legs with the body. From a medical point of view, dishes made from this crab are often recommended to be consumed to improve vision, as well as for anemia and various cardiovascular diseases.
Section 7. How to cook Kamchatka crab?
Properly cooked Kamchatka crab, photos of which can be seen on the menus of the most luxurious restaurants on the planet, has the most tender meat and a subtle aroma of sea freshness.
Is it possible to try it, as they say, at home? Surely! Not everyone knows that there is a simple and fairly quick way to cook crab that anyone can handle. So, first of all, this crustacean should be boiled in very salty water, and to improve the taste, it is recommended to add allspice, carrots, leeks, onions, celery root and even wine to the broth. How to calculate everything correctly? Very simple. For example, for a crab weighing 1.5 kg, you need to take a pan that can hold at least 30 liters of water and 4 liters of wine.
You need to cook it for at least 15 minutes, but at the same time, when cooking, it is important to ensure that the crab is not overcooked, otherwise its meat will resemble rubber more than a delicious delicacy.
Kamchatka crab, photos and detailed descriptions of dishes from which are found in almost all cookbooks, is a great way to surprise even the most fastidious gourmet guests.
Naturally, when setting the table, you cannot do without a beautiful presentation of the dish. For example, why not place the prepared crab on a dish along with herbs to make the delicacy look as if it were alive? Tempting? By the way, please note: it is advisable to first cut the crab shell near the claws. This will make cutting it much easier.
Crabs are marine crustaceans or decapod short-tailed crustaceans. The meat of almost all sea crayfish can be eaten, but only the commercial type of crab can be freely purchased. For the buyer, the size of the crabs that are available in the retail chain almost always matters. Some people choose a larger specimen, especially if the crab is needed for a festive feast; for others, for financial and other reasons, it is more convenient to purchase a smaller specimen.
If we consider in terms of the size of male and female crabs, then in commercial species, as a rule, females are somewhat smaller in size than males. If we consider all the representatives from the world of crabs, then the tiniest crab - the pea or the Black Sea pinnoterese - lives in the Black and Azov seas. The size of this baby is less than 10 mm. Of course, such crumbs, which cannot even be seen in the water, are of no commercial or food interest to humans. And here buy Kamchatka crab, one of the largest representatives of marine crustaceans, is the dream of many seafood lovers. Let's try to figure out whether there are other crabs that can compete with the Kamchatka crab in size.
Commercial species of crabs in Russian seas, their sizes
Today, it is quite easy to buy crab in a retail chain, especially considering that almost all commercial species of sea crabs are .
Kamchatka crab
In the English version, this sea animal is called the red king crab. Among all the crabs that live in the Seas of Okhotsk, Japan, and Bering, this is the largest and heaviest species. By their age limit, and king crabs live up to a quarter of a century, the size of the carapace - carapace - in males can exceed 20 cm and reach 25 - 26 cm, in females up to 20 - 22 cm. The weight of males at 18 - 19 years old can reach 5 - 6 kg, although the average weight of harvested crabs is 2.5 - 3.0 kg. The span of the king crab's walking legs can be 1.5 - 1.8 m. But the Kamchatka crab is not the only representative of such a serious size that is subject to catch in the Russian seas.
Crab blue
The English version of the name of this sea crayfish sounds like blue king crab. The name is associated with large blue spots that are located on a brown background. Its size is close to the Kamchatka crab. There are males weighing 4.5 - 5 kg with a carapace size of 22 cm. By the age of eight, blue crabs become capable of reproduction. At this age, they molt no more than once a year, during this period their size increases by no more than 1.5 cm. You can buy blue king crab quite often, since this species is actively caught in the same seas as red king crab.
Equal-thorn crab
This sea crayfish is also subject to industrial fishing. Most often, the shell of this crab is colored yellow. In weight and size, this inhabitant of the Okhotsk and Bering Seas is not inferior to the Kamchatka crab. Males with a weight of up to 6 - 7 kg and a carapace of 25 cm are not uncommon. If you can buy a Kamchatka crab with an average weight of 2.0 - 3.0 kg, then the average fishing weight of a brown king crab is 1.8 - 2.1 kg. Unlike the two previous relatives, this crab is almost absent from the Sea of Japan and the main catch takes place off the coast of Sakhalin and the Kuril Islands.
Spiny crab
The English name is associated with the color of the shell - brown king crab, so the chitin has a rich dark brown color. Large males weigh more than 3.0 kg, and the average fishing weight is about 2 kg. Females have a carapace size of up to 15 cm, males - up to 18 cm. It lives in all seas of the Far East.
When we talk about the above species for which commercial fishing is permitted, it should probably be clarified that we are talking about craboids, which are closer to hermit crabs than to crabs, since they have only four pairs of well-developed legs, and the fifth pair is strongly reduced and hidden under the shell.
The question may arise, but is it possible to buy crab, which refers to real sea crabs and what size are they?
True crabs include:
strigun opilio;
Baird's Strigun;
four-cornered hairy crab;
Strigun angulatus;
Strigun red.
The sizes of these representatives of decapods are different. The largest is opilio, its shell measures 15 - 17 cm, and its weight reaches 2.5 kg.
Almost as good as opilio and Baird's strigun, with a carapace size of 12 - 16 cm and a weight of 0.8 kg to 1.2 kg.
Angulatus and red snow crab generally weigh less than a kilogram, the same weight as the hairy crab, which is very loved by the inhabitants of the Japanese islands.
A common feature of real crabs is the presence of five pairs of developed walking legs. What they have in common with craboids is the shape of the carapace, the presence of claws on the first pair of limbs, and of course the taste of the meat and its composition.
If you buy Kamchatka crab in shell, then you can distinguish it not only by size, but also by shape, but if you buy strigun meat opilio and red king crab meat without shell, then it is quite difficult for taste to distinguish them. The meat of all commercial crabs has approximately the same taste, calorie content and chemical composition.
Residents of different countries also have the opportunity to buy crab, which is exported from Russia.
The number of different families of crabs reaches almost one hundred, and the number of species - up to seven thousand.
Although crabs are decapoded marine invertebrates, in addition to five pairs of walking legs, they also have three pairs of very short thoracic legs. These legs are small and do not participate in movement. Their role is to participate in nutrition and respiration. Since sometimes the gills are located either next to the pectoral legs or directly on them.
The role of skin in crabs is performed by a hard chitinous layer, which itself has a unique composition. It is noteworthy that, unlike the skin of other animals, chitin does not stretch or increase in size as it grows. Therefore, crabs molt regularly. The periods between molts may lengthen as the crab matures.
Despite the fact that people have been catching crabs and eating them for many thousands of years, the biology of these animals still has many mysteries.
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After the introduction of a food embargo in 2014 on agricultural products, raw materials and food from countries that applied economic sanctions against Russia, there is a shortage of many products on the market. European cheeses, fruits, fresh berries and seafood have disappeared from restaurant menus. Many establishments had to not only look for alternative suppliers, but also completely change their concept. As a result, over the past few years, restaurants have appeared in Moscow, the menu of which contains mainly Russian ingredients, primarily meat: “Voronezh”, “Ryba Net”, “Yuzhane” and many others. Russian fish and seafood also began to be in demand, and crabs replaced lobsters. To find out all about the latter, The Village spoke with the chef of the Erwin restaurant. RiverSeaOcean" by Alexey Pavlov and compiled a detailed guide to these crustaceans.
What kind of crabs are served in Moscow restaurants?
There are many varieties of crabs, but restaurants usually use only five to seven types, since other crustaceans have little meat. The most popular crab is Kamchatka crab. Other types are most often served to attract guests. Crabs differ among themselves in habitat and seasonality - these factors affect the appearance of the crustacean, its filling with meat and taste.
Kamchatka crab
Weight: from 3 to 7 kilograms
Catch: from September to April
Peculiarity: large size, caviar
Price: 10 thousand rubles for a live crab
It is also called royal, since it is the largest among the crustaceans of the Far East. Kamchatka crab began to be bred in the Barents Sea in the mid-20th century, from where it is now caught and delivered to restaurants around the world. Kamchatka crab meat consists of dense and thick spaghetti-like fibers and usually has a sweetish taste. Although some crabs of this species may be salted, this depends on the sea in which the crustacean lived.
One of the features of this species is caviar. It is the size of a grape and has a light purple color when raw. Sometimes it occurs when ordering a whole crab. No one extracts caviar separately: it is expensive and illegal.
spiny crab
Weight: from 800 grams to 1.8 kilograms
Catch: cannot be caught during the molting period (mid-summer)
Peculiarity: spines all over the shell
Price: 6 thousand rubles for a live crab
The shell of this crab is covered with sharp spines from the head to the claws - hence the name. Despite its small size, the spiny crab is not inferior to the Kamchatka crab in terms of meat content. It tastes just as juicy and sweet, although it has less fiber than king crab. The “thorn” is brought to Moscow from the southern part of the Bering, Okhotsk and Japanese seas.
Hairy crab
Weight: from 900 grams to 2 kilograms
Catch: from August to October
Peculiarity: unusual meat structure, liver
Price: 400 rubles per 100 grams
Hairy crab is brought to Moscow from the coastal waters of Sakhalin. Hair crab is filled with meat and is fully used in cooking, just like king crab and spiny crab. This crab has a short season - only three months, but even during this time it contains a lot of meat. It has a rather specific taste, as it consists of very thin fibers, similar to threads.
The main value of the hairworm is the liver. It has the same positive effect on the human body as, for example, oysters. The hairworm's liver is small, about the size of a teaspoon, gray in color and tastes like a delicate dessert with sourness. However, the liver is not found in all hairworms.
frog crab
Weight: from 200 to 400 grams
Catch: during the whole year
Peculiarity: appearance
Price: 200 rubles per 100 grams
The crab got its name because of its resemblance to a frog: it has a large shell and small claws on top and bottom. There is little meat in the “frog” - only in the back of the crab, like crayfish. Its structure resembles pulp, and its taste is similar to fish such as sea bass or sea bream.
Frog crab is harvested in the Indian Ocean near the Seychelles and supplied to Russia in boiled and frozen form. Some restaurants may serve the whole frog to make the dish interesting. But due to the strong shell, it is not easy to get to the meat, so it is better to ask to fillet the crab and process it.
Blue crab
Weight: from 400 to 500 grams
Catch: during the whole year
Peculiarity: the most tender meat
Price: 300 rubles per 100 grams
The blue crab lives on the Atlantic coast of North and South America, as well as in the Baltic, Mediterranean, Adriatic and North seas. This crustacean has the softest and most tender meat due to the lack of fiber in it. But poor fillability - only 40% meat of the total body weight. Therefore, blue crab is usually used as an additional ingredient rather than as a main dish.
Snow crab
Weight: from 200 to 400 grams
Catch: from October to April
Peculiarity: looks like a spider
Price: 300 rubles per 100 grams
Snow crab is also called opilio. It is supplied to Moscow from Murmansk. Restaurants most often offer its phalanges - long (about 30 centimeters) and thin, like pencils, with a small amount of sweetish meat, which is not very easy to get. Also used in cooking are the claws and “fists” of this crab. Opilio has dense, juicy and vitamin-rich meat.
How are crabs caught and prepared?
All crabs are caught, in principle, the same way - it’s just that some do it legally, and some don’t. Restaurants deliver crabs live, as well as fresh frozen and boiled-frozen. Live crabs are transported by plane in special containers with small briquettes that cool the container. After transportation, the crab is allowed to rest in its natural environment, otherwise it will die, and only then is it delivered to restaurants.
Live crabs can only be found during the season, since the rest of the time the crustaceans go to the bottom and feed from the resources of their own body - they cannot be caught. To cook crabs throughout the year, restaurants buy them fresh frozen or boiled-frozen. The taste of this meat is no different from freshly cooked meat.
Crabs can be prepared in different ways, it all depends on the imagination of the cook. But most often they are simply boiled or steamed, lightly treated with olive oil, herbs and served. Cooking time depends on the weight of the crab, but on average 30 minutes.
What do you eat crabs with?
Most often, crabs are served with hot melted butter, to which garlic and finely chopped herbs (for example, wild garlic) are added if desired. Among the sauces, the best is a simple aioli based on homemade mayonnaise. Some people like to eat crab with tartar, wasabi mayonnaise and other bright-tasting sauces, but they can overpower the taste of the meat. As for dishes with crab, it is better to combine it with simple products - cereals, spaghetti, bread. Classic dishes with crab include risotto, fettuccine, and bruschetta. Rose wine also goes well with crabs.
In the places where crabs are brought from, they are considered a completely common product. Some people specifically travel, for example, to Murmansk to try crab meat. But if we talk about large enterprises involved in growing these crustaceans, they do not sell anything to the locals, preferring to give all the goods to wholesalers, especially abroad.
How to eat crabs correctly?
The easiest way to cut a crab is to ask the cook to serve it to you open. If you want to do everything yourself, then you should pick up scissors and start, for example, with the phalanx. The phalanx must be cut at the root and cut across to the very end on both sides. After which you need to remove the top cover and remove the meat with a special device that looks like a spatula with a clove. The claw attachment has three threads that hold everything together, so you have to pull the meat onto the plate from them.
To get the meat out of the “fist”, you just need to break it with a special hammer. The meat in the “fists” differs from the meat in the phalanges in its denser structure. As for the crab head, there is practically no meat in it. But if you wish, you can open it too. To do this, cut the crab with scissors starting from either side. Crabs only have a hard shell, and the bottom is soft, so it can be cut through without difficulty.
For those who saw Kamchatka crabs for the first time in their lives, these animals make a great impression.
In terms of its size, the Kamchatka crab is an outstanding representative not only of decapods, but also of all crustaceans. The characteristic structural features of crustaceans, reproduced in the Kamchatka crab on a large scale, are strikingly striking even at the most superficial glance at this animal.
The width of the shell of the average male Kamchatka crab is about 16 centimeters, the span of its legs is almost 1 meter, and its weight exceeds 2 kilograms. The largest specimens reach 25 centimeters in carapace width, one and a half meters in leg span and 7 kilograms in weight.
The body of the Kamchatka crab consists of a cephalothorax, covered with a common shell, and a belly, folded under the cephalothorax. Therefore, if you look at a crab from above, only its shell and legs are visible. A powerful shell with large sharp spikes reliably protects the animal and, in addition, serves as a support for the muscles. The shell, like that of the crayfish, fuses with the body only on the back, and on the sides it lags behind the walls of the body and hangs down like the sides of a jacket, covering the gills. The gills in the resulting cavities are protected from damage and at the same time are easily washed with water. In front of the cephalothorax are attached two pairs of antennae, eyes on stalks, jaws and legs. The front edge of the shell is armed with a sharp outgrowth that protects the eyes.
The abdomen of the crab, always tucked under the cephalothorax, in females bears special appendages for bearing eggs. The abdomen contains the intestines and internal genital organs. The first pair of crab legs is armed with powerful claws, the next three pairs are used for movement, and the last pair of reduced legs is always under the shell and is used for cleaning the gills. The muscles of the walking legs are very well developed.
What do Kamchatka crabs eat?
Kamchatka crabs are predators. They eat marine bottom polychaetes, mollusks, amphipods, echinoderms, small sea acorns and other bottom animals. The crabs tear their prey with their claws and, using their legs and jaws, crush, grind and send it into their mouths. The right - large - claw is used to crush shells of mollusks and skeletons of sea urchins. With its left claw, the crab can tear only soft prey. Very interesting experiments were carried out to find out what sense crabs are guided by in their search for prey. Food was lowered into a large aquarium where Kamchatka crabs were kept. The animal immediately reacted to the smell with characteristic movements of the antennae and began searching for prey. The crab cannot determine the direction to the prey by smell, so it begins to move slowly, feeling the bottom with the ends of its claws. The crab lowers its claws vertically downwards and, touching the ground with the ends of its claws, quickly opens and closes them, as if snapping scissors, to see if anything gets caught. These probing movements are very energetic and "nervous".
The crab searches blindly, describing the most incredible loops along the bottom of the pool. As it approaches the feeder, when the smell of food intensifies, the crab becomes very excited and probes the bottom with its claws even more often. However, even in close proximity to the food (for example, at a distance of 1 centimeter from the end of the claws to the food), the crab repeatedly misses and moves away from it again. This suggests that the crab's sense of smell and vision are poor helpers, and it finds its prey only through touch.
Finally, the crab probes for food with the tip of its claw and quickly grabs it with one claw or both at once. In search of prey, the animals lost an unusually large amount of time, traveling an unnecessary long distance.
Kamchatka crabs spend their entire long lives wandering, repeating the same route every year. The Kamchatka crab is an exclusively running animal and is completely unsuited to either swimming or burrowing into the ground. The crab cannot burrow, because then its open gills can become clogged with silt. Powerfully developed leg muscles allow you to cover long distances. The crab runs both forward and sideways, alternately throwing out and bending its walking legs. The claws of the feet act like pegs stuck into the ground. The body is supported by weight when walking. The speed of movement of Kamchatka crabs in a straight line reaches 2 kilometers per hour. However, the crab usually moves in zigzags, and the distance it travels per day does not exceed 10-13 kilometers. Individual crabs wander in different directions, and the speed of movement of the entire school is only 2-4 kilometers per day. Crab shoals move throughout the year within their migratory area. The size of such areas for one school is almost 200 kilometers. Some crabs stray from their schools and move into schools in neighboring areas. The reason for such transitions is strong competition for food. Animals often move to areas where fishing is more active. There, the number of crabs drops significantly due to fishing, and competition for food decreases.
Where do Kamchatka crabs winter?
The wintering grounds of crabs are located quite far from the coast at depths of 110 to 200 meters. In fact, the crab does not hibernate, but continues to lead the same active lifestyle in winter as in summer. The move to depth is explained by lower water temperatures in shallow waters and the formation of ice. In the spring, when the bays of the sea are cleared of ice, the crabs move to shallower areas. During this period, males and females of the king crab stay in separate herds and move to the shore in parallel paths. Female crabs carry eggs on their abdominal legs, which have been developing since last year, and halfway through the adult crabs' journey to the shore, a mass hatching of larvae occurs. The fully developed crab embryos in the eggs, whose translucent eyes gave them the name “caviar with eyes,” tear the shells of the eggs into two halves and float up into the water column.
Reproduction of Kamchatka crabs
About a month after the start of migration, schools of males and females meet in shallow waters and mix. The mating period begins. The females at this time look very unpresentable: a dirty shell overgrown with barnacle shells, empty egg shells on the abdominal legs. Nevertheless, the males choose their mates and clamp the claws of the females with their claws. Couples can remain in this “handshake” position for 3 to 7 days. Then the males help the females molt by pulling off the contaminated old shell from them, and attach spermatophores to the bases of the third pair of walking legs of the female. After this, the partners separate. After some time, the female lays eggs on her abdominal legs, which are fertilized from the spermatophore and which the female carries on herself until next spring.
After mating, the schools of females and males again migrate separately, now the crabs go in search of food and feed all summer. Before the summer migration, the males molt, but in complete solitude, hiding among the underwater rocks. During the feeding period, crab schools gradually move from one field to another at an average speed of about 4 kilometers per day, destroying a significant number of bottom animals.
Where do Kamchatka crabs live?
The largest quantity of Kamchatka crab, as its name suggests, is found off the coast of Kamchatka, as well as in Primorye. Its distribution area goes from Posiet Bay through the northern part of the Sea of Japan, through the Sea of Okhotsk and most of the Bering Sea along the Aleutian Islands to the Pacific coast of Canada.
Origin and description of the species
The Kamchatka crab (Paralithodes camtschaticus) owes its name to its external resemblance to crabs, however, according to the zoological classification, it originated in the process of evolutionary development from hermit crabs belonging to the Craboid family, the general genus Paralithodes.
The main difference from crabs is the shortened fifth pair of walking legs hidden under the shell, as well as the irregularly shaped, asymmetrical abdomen with chitinous scutes in females. A short pair of limbs in hermit crabs serves to hold the shell. In the process of evolution, the Kamchatka crab stopped living in a shell and therefore the need to hold it disappeared. The fifth pair of legs is used to clean the gills.
The crab moves with the help of four pairs of limbs, moving them in turn. It moves at a fairly high speed, the direction of movement in this species is to the side.
The abdomen, bent and shortened, has small plates and microlegs, the asymmetrical arrangement of which confirms the origin of the arthropod from species in which the abdomen is twisted in a spiral shape.
Video: Kamchatka crab
The senses of touch and smell are provided by the front antennae with sensitive cylinders located on them. This species feature has a significant impact on feeding behavior, helping in the search and selection of food.
As the individual grows, a change in the frame skeleton occurs, or molting. The frequency of molting at the beginning of life, especially during the development of larvae, is high and occurs much less frequently, up to 1-2 per year in an adult, and by the end of life it happens only once every two years. How often crabs should molt is regulated by special glands located on the eyestalks. Before shedding the old frame, the soft parts of the arthropod are already covered with a still weak, pliable shell. The Kamchatka crab lives on average about 20 years.
Appearance and features
The crab's body consists of two parts - the cephalothorax, located under a protective shell, and the abdomen, folded under the cephalothorax. The eyes are protected by an overhanging shell or beak. The carpax has sharp protective spine-like spines, 6 of which are located above the heart and 11 above the stomach area.
In addition to the protective function, the shell also serves as a support and exoskeleton, because muscle fibers that carry out movements are attached to it from the inside. On the lateral surfaces of the frame shell there are respiratory organs - gills. The nervous system is represented by a chain of interconnected nerve nodes located on the underside of the cephalothorax and abdomen. The heart is located at the back, and the stomach is located at the head.
Of the five pairs of legs, the crab uses only four to move. The reduced fifth pair is hidden under the shell and is used to clean the gills.
Interesting fact. The use of claws in the Kamchatka crab differs in the nature of the function performed. With its left claw, the crab cuts softer food, and with its right claw it crushes hard food - sea urchins that live on the bottom, the shells of various mollusks. The claws differ in size; the right one is larger, performing more difficult work.
In males, the width of the body varies from 16 to 25 cm and the weight reaches 7 kg. The distance between the ends of the long legs of the largest individuals is about 1.5 m. Females are smaller in size - body up to 16 cm, weight on average 4 kg. The female is also distinguished by the presence of a round and irregularly shaped abdomen.
The color of the shell of the Kamchatka crab is red with a brown tint on top, areas and inclusions in the form of purple specks are noted on the side surfaces, the color of the crab is lighter below - from white to yellowish.
Where does the Kamchatka crab live?
Wide distribution is noted in the northern part of the Pacific Ocean, where arthropods of this species are more abundantly found in the Kamchatka region in the Sea of Okhotsk, as well as in the Bering Sea. The crab also lives off the American coast in Bristol Bay, Norton Bay and near the Aleutian Islands. In the Sea of Japan, habitat is noted on the southern side.
Interesting fact. Biologists of the Soviet Union developed and carried out the relocation of the species to the Barents Sea.
The new environmental conditions are different from the usual conditions of natural habitat (lower water salinity, temperature ranges, annual temperature changes). The theoretical preparation process took place since 1932, induced by the main goal of achieving economic profit from fishing in its waters, avoiding high competition from Japan and other countries.
The first attempts to transport crabs were carried out by rail and were unsuccessful - all individuals died, the travel time was long, it took more than 10 days. After this, in the 60s, air transportation was carried out, taking a short time. This is how the first batches of arthropods were delivered and acclimatized. Later, in the 70s, transportation took place in specially equipped cars and was the most successful.
Currently, as a result of the process of invasion, an independent population unit with a high replenishing and self-regulating population has formed in the North Atlantic. There is an industrial catch of large males. Catching juveniles and females is prohibited.
What does the king crab eat?
The food for this species is very diverse and the crab is inherently an omnivorous predator.
Food objects are all inhabitants of the seabed:
- various shellfish;
- plankton;
- worms;
- sea urchins;
- crustaceans;
- ascidians;
- small fish;
- sea stars.
The young feed:
- algae;
- hydroid organisms;
- worms.
During their lives, representatives of this species make mass movements for food purposes. Moving from one ecosystem to another, the dominant species in a particular system become food.
Powerful claws serve as an excellent tool, and the crab easily obtains the necessary food. Moreover, when killing the prey, the crab does not eat it completely, and most of its mass is lost. Crabs also eat the corpses of fish and other marine organisms, acting as a water purifier. After the introduction of the crab into the waters of the northern seas, there is still no clear opinion about the impact of the settler on local biosystems as a whole.
Some scientists criticize the experiment, fearing for the presence and numbers of native species of inhabitants of the northern seas, with which the Kamchatka crab competes in nutritional needs and on which it feeds. After all, by consuming certain types of organisms en masse, the crab can lead to their depletion and even extinction. Other scientists speak favorably of the results of the introduction, emphasizing economic benefits.
Interesting fact. At different periods of their life cycle, arthropods prefer different foods. For example, an individual that is about to molt in the near future preferably chooses organisms with a high calcium content, such as echinoderms, as food.
Features of character and lifestyle
The strong frame of the arthropod, serving as protection and support, at the same time prevents growth between the moments of its change. The animal grows only in a short period (usually no more than 3 days), when the old hard frame is discarded, and the new one, still soft and pliable, does not interfere with its rapid increase in size. After a growth spurt, the chitinous cover is intensively impregnated with calcium salts and overall growth stops until the subsequent molt.
The frequency of shell changes varies over the course of life:
- up to 12 times after the formation of the larva during the year;
- up to 7 times, less often in the second year of life;
- 2 times during the year during the period of life from the third to the ninth year of an individual’s life;
- 1 time from the ninth to the twelfth years of life;
- Once every two years, from the age of thirteen until the end of your life.
During molting, the animal tries to find shelter in depressions or rock cracks, as it becomes defenseless without a strong frame.
Interesting fact. Molting affects not only the outer cover of the crab; internal organs are also renewed - the membranes of the esophagus, stomach and intestines are renewed. The ligaments and tendons with which muscle fibers are attached to the exoskeleton are also subject to renewal. Cardiac tissues are also renewed.
A representative of this species is a rather active arthropod, constantly performing migratory movements. The route of movement does not change, repeating itself every year. The reason for migration is seasonal changes in water temperature and the availability of food, as well as the reproductive instinct.
So, with the onset of winter, the crab sinks along the bottom into deep waters within 200-270 m. With warming, it returns to the warm shallow waters filled with food. Crabs migrate en masse, gathering in groups of varying numbers. Males are ready to breed when they reach ten years of age and females are seven or eight years old.
Social structure and reproduction
After the onset of spring, males begin their journey to shallow water. Females move in the same direction, but in separate groups. The female carries already ripe eggs on legs located near the abdomen. Closer to shallow water, larvae emerge from the eggs and are carried away by the current. By this time, new eggs have already been formed in the female’s genital organs, which are yet to be fertilized.
With the beginning of molting, individuals of both sexes come closer and form a characteristic pose - the male holds the female with both claws, reminiscent of shaking hands. The holding continues until the end of the moult; sometimes the male helps the chosen one to free herself from the old frame. After the completion of molting (on average from three to seven days), the male releases a ribbon with germ cells - spermatophores, which is attached to the female’s legs. The male, having completed the mission, leaves and also moults.
After some time (from several hours to several days), the female spawns eggs (from 50 to 500 thousand), which, when they meet the male’s ribbon, are fertilized. A special sticky substance collects the eggs together and attaches them to the villi on the female's abdominal legs, where they undergo a development cycle until the following spring, for 11 months. The female spawns eggs only once a year, in the spring, but males can mate with several females.
The larvae that have just hatched from the eggs remain in the water column for about two months and are transported by the current; at this stage of development, up to 96% of the larvae die. Afterwards, the surviving larvae sink to the bottom, into algae thickets, where they live for three years. They molt frequently and go through several stages of development. Then the young individuals move to sandy bottom areas. Migration begins after reaching 5 years of age, sometimes 7 years of age.
Natural enemies of Kamchatka crabs
Adult large representatives of the species have few natural enemies, since the crab has excellent protection - a reliable and durable shell, which in addition is covered with sharp spine-like needles. Only large marine mammals are able to overpower an adult crab.
Smaller individuals have a greater number of enemies, among them:
- predatory fish;
- Pacific cod;
- halibut;
- marine;
- bulls;
- octopuses;
- large crabs of different species (intraspecific cannibalism is noted).
During the molting period, the crab becomes absolutely vulnerable and is forced to seek shelter. Man is not one of the natural enemies of the species, however, given uncontrolled commercial fishing and poaching, man has every chance of becoming a species enemy. Therefore, quotas for catching royal arthropods are determined at the state level in order to use population reserves as carefully as possible without undermining their numbers and ability to recover.
Human activities indirectly negatively affect marine life, in particular the Kamchatka crab. Industrial chemical waste, plastic, and petroleum products pollute the vast seas and oceans, negatively affecting all flora and fauna. As a result, entire species are vulnerable to depletion or are on the verge of extinction.
Population and species status
King crab migration occurs in groups of individuals, with females and males moving separately, meeting only once a year, in the spring, for mating. Juveniles also move separately, creating groups of young. The size of the crab population in the Kamchatka region is currently significantly reduced, for the same reasons of large-scale and uncontrolled commercial fishing.
In the Barents Sea, where the species was artificially introduced, the situation is the opposite. Due to the absence of many natural enemies regulating the population, the royal arthropod quickly spread throughout the coastal territory of the Barents Sea. According to rough estimates, the population size in 2006 was more than 100 million individuals and continues to grow.
The polyphagous predator quickly exterminates the indigenous species of many crustaceans, mollusks and others, which rightly raises concerns among many biologists for the continued existence of a stable ecosystem in the Barents Sea.
Since 2004, Russia began commercial fishing. Allowable fishing volumes are determined each year based on the current situation in the estimated population size.
Kamchatka crab An interesting arthropod with a special development cycle. Representatives of this species have successfully completed the process of introduction and acclimatization into the northern Barents Sea. Scientists predict differently how this invasion will affect the integrity of the marine ecosystem in the future.
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