Black Sea crab: size, what it eats, description. Crabs Interesting facts about crab vision

Originally, the Chinese mitten crab lived in river systems Yellow Sea. But in 1912, a small crustacean (only 7 cm in size) was accidentally brought with ballast water from Germany. It very quickly settled along the riverbeds of the Elbe and Weser rivers. In the 20th century, along with ships, it moved to the Netherlands, Belgium, France, Poland, and Scandinavia. Also got into North America. The Chinese mitten crab is recognized as a highly dangerous invasive species.

A crab that grows its own food

The yeti crab grows bacteria on its own claws, which are later eaten by the crab. Such a crab was first discovered in 2005 at a depth of over 2000 meters in the area of hydrothermal vents in the South Pacific Ocean.

We are accustomed to the fact that crabs are not very large in size. But the exception to the rule is the Japanese spider crab, which reaches truly large sizes. Spider crabs weigh up to 19 kg with a leg span of up to 3.8 m. And these crabs live for a very long time: up to a hundred years.

Male crabs found off the coast of Australia have one claw much larger than the other. These crabs got their name because they seem to call females to them by moving this claw. The males of one of the species of crab Uca mjobergi went further - if they lose a large claw in a fight with another male, then they grow another one larger size, although somewhat weaker than the previous one. However, for females its appearance becomes preferable, and other males try not to engage in battle with the owner of such a massive claw.

Samurai face on a crab shell

Heikegani crabs live off the coast of Japan; the pattern on their shells is very similar to the face of an angry samurai. According to science popularizer Carl Sagan, this species owes its appearance to unintentional artificial selection. One generation of Japanese fishermen after another, catching such crabs, released them back into the sea, considering them to be reincarnations of samurai killed in battle. By doing this, the fishermen increased the heikegani's chances of further reproduction and increasing their numbers among other crabs.

A portion of statistics

The earliest crab fossils date back to Jurassic period, that is, about 150,000,000 years ago, crabs already existed.

Up to 1.5 million tons of various crabs are caught annually.

"Crab Mentality"

The essence of this phenomenon is that a crab placed in a bucket can get out of it, but if there are several crabs in the bucket, then none of them will be able to gain freedom, since everyone will collectively cling to the “fugitive” and interfere with each other implement the liberation scenario. This metaphor is often transferred to human society, as well as to competition in various social hierarchies.

The most interesting facts about crabs

Crabs: interesting facts

Planet Earth has about five thousand varieties of crabs. And each of them, although completely different in appearance, the body structure remains the same for all - eight legs and two claws.

About 8.1 million tons of crabs are eaten annually in restaurants and homes around the world, given such a long breeding period, this species of crab is in danger of extinction.

Crabs are very aggressive towards each other. Males often fight for the right to possess a female.

Crabs become capable of reproduction at the age of 8-10 years.

How do crabs reproduce? The male attaches his sperm, covered with a water-insoluble coating, to the female's abdomen. Afterwards, the female lays eggs and attaches them to the lower part of the body, under a special protective plate, where they mix with sperm and fertilization occurs. After incubation period, which lasts approximately 11.5-12 months, the hatched crab larvae fall to the bottom. During the growth process, the larva molts up to 5 times. She becomes more or less crab-like at the age of three.

The crab's teeth are in the stomach.

A person walks relying on his hard skeleton, but a crab has an external skeleton, and inside only internal organs and muscles.

40% of the crab's weight is meat.

If a crab loses a claw, it can grow a new one. True, it will be smaller in size and will not be as beautiful as the first one.

The Japanese spider crab is oldest species crabs in the world, and is also considered to be the deepest.
Moreover, it has the longest life expectancy - 50 years.

These crabs become capable of reproduction at the age of 10 years.
The spider crab's limb span is about 3.3. meters, and the body itself is only 60 centimeters. The mass of such a giant crab is only about 20 kilograms.

It is believed that this species prefers to live at a depth of 200-300 meters, but there have been individuals that feel good at depths of 800 meters and above.

From a zoological point of view, crabs and crayfish belong to the same species. These animals have their own categories of definition and their own hierarchy. And among them there are also giants, which is what king crab, which, despite the name, is considered one of the

Appearance of Kamchatka crab

Appearance king crab really very similar to others, but still the animal belongs to the craboids and is distinguishable primarily by its reduced fifth pair of legs.

This is one of the largest representatives of its species, belonging to the Lithodidae family. Size adult Kamchatka crab the male reaches 25 cm in cephalothorax width and 150 cm in leg span, with a weight of 7.5 kg. Females are smaller, weighing about 4.3 kg.

The body of the crab consists of a cephalothorax, located under a common shell, and an abdomen. The abdomen, or abdomen, is tucked under the chest. The shell in the area of the heart and stomach is equipped with sharp spines, of which there are 6 above the heart and 11 above the stomach.

Pictured is Kamchatka crab

Thus, it protects the soft body of the crayfish, and at the same time serves as a support for the muscles, since the animal does not have a skeleton. There are gills on the sides of the shell.

On the front of the shell there are protruding growths that protect the eyes. The entire nerve cord is located on the lower side of the body. The stomach is located at the head of the body, and the heart at the back.

Kamchatka crab has five pairs limbs, four of which are walking, and the fifth is used for cleaning the gills. Kamchatka crab claws each has its own purpose - with the right it breaks hard shells and crushes hedgehogs, while with the left it cuts softer food.

The female can be distinguished by the more round structure of the abdomen, which in the male is almost triangular. The color of the crab's body and legs is red-brown above and yellowish below. There are purple spots on the sides. Some individuals are brighter colored appearance Kamchatka crab can be assessed by photo.

Habitat of the Kamchatka crab

This large animal lives in many seas. The main range is in the Far Eastern region and northern regions the seas that wash it. This is how the crab lives in the Sea of Japan, Okhotsk, and Bering. Inhabits Bristol Bay. The range is concentrated near the Shantarsky and Kuril Islands, Sakhalin and most of all in Kamchatka.

Kamchatka crab was induced into the Barents Sea. This process was long and complex, starting theoretically back in 1932. Only in 1960 was it possible for the first time to transport adult individuals from Far East.

Between 1961 and 1969, the bulk of crabs were imported, mainly using air transport. And in 1974, crab was caught for the first time in the Barents Sea. Since 1977, these animals began to be caught off the coast of Norway.

On at the moment the population has grown very much, the crab has spread along the coast of Norway to the southwest, as well as north to Spitsbergen. In 2006, the crab population in the Barents Sea was estimated at 100 million individuals. The crab lives at a depth of 5 to 250 meters, on a flat sandy or muddy bottom.

Lifestyle of the Kamchatka crab

The Kamchatka crab leads a fairly active lifestyle; it constantly migrates. But his path is always built along the same route. Travel speed is up to 1.8 km/h. Crabs walk forward or sideways. They do not know how to burrow into the ground.

In the photo there is a blue Kamchatka crab

During cold periods, the crab goes deep to the bottom, dropping to 200-270 meters. With the arrival of heat, it rises to the warm upper layers of water. Females and juveniles live in shallow water, while males move a little deeper, where there is more food.

Once a year, an adult Kamchatka crab moults, shedding its old shell. By the time the old cover disappears, a new, still soft, shell is already growing under it. The molting process takes about three days, during which the crab does not like to be seen and hides in holes and rock crevices. “Naked” females are guarded by males.

Molting for the “stronger sex” takes place later, around May, when the water temperature reaches 2-7 C⁰. In addition to the chitinous cover of the animal, the outer membranes of the heart, stomach, esophagus and tendons also change. Thus, the animal is almost completely renewed every year and gains new mass.

Young animals molt frequently - up to 12 times in the first year of life, 6-7 times in the second year and then only twice. After reaching the age of nine years, crabs become adults and molt only once a year, and old 13-year-old individuals only molt once every two years.

Nutrition of Kamchatka crab

The Kamchatka crab feeds on bottom inhabitants: marine, various, starfish, small fish, plankton, arrows, . Kamchatka crab is practically omnivorous predator.

Young individuals (fingerlings) feed on hydroids. Using the right claw, the crab extracts soft meat from hard shells and shells, and eats food with the left claw.

Commercial species of crabs

In the Far Eastern seas there are many species of crabs available for catching. In those parts you can buy Kamchatka crab or anyone else.

The Baird's snow crab is a smaller species and can sometimes mate and produce hybrids with the Opilio snow crab. These species weigh up to approximately 1 kg. and have a caracapus size of about 15 cm. The red snow crab lives in the Sea of Japan. This is a small animal on average 10-15 cm. Named for its bright scarlet color.

Prices on Kamchatka crab vary, you can buy a whole crab, live or frozen. There is an opportunity to purchase phalanges of Kamchatka crab, claws - with or without shell, meat and various ready meals from it. The cost at catch sites is significantly lower than when taking into account delivery to the regions. The price of a live crab is about 10,000 rubles.

Kamchatka crab meat It is very valuable for the whole body due to the presence of vitamins and microelements in it. It is good for vision, strengthening cardiovascular system and general improvement in the condition of the body.

Reproduction and life expectancy of the Kamchatka crab

During spring migration, females carry eggs with embryos on their abdominal legs, and their ovaries contain a new portion of unfertilized eggs. On the way to shallow water, larvae hatch from the outer eggs.

Then the females and males meet, and molting occurs. The male helps the female get rid of the old shell, and when this happens, he attaches a ribbon of spermatophores to her walking legs, after which he goes to the depths to feed.

The female spawns eggs and fluid to activate spermatophores. The number of eggs reaches 300 thousand. The eggs are attached to the female's abdominal legs, which she constantly moves, washing the eggs with fresh water. During the warm season, the eggs develop, but freeze in the winter and growth is activated again only in the spring, during the period of migration and warming of the water.

The photo shows the claws of a Kamchatka crab

The hatched larvae do not at all resemble crabs - they are oblong creatures with a long abdomen, without legs. For about two months, the larvae are carried along the seas by currents, during which time they manage to molt four times.

Then they sink to the bottom, molt for the fifth time and only then acquire legs, a shell, and their abdomen becomes much shorter. After another 20 days, the larva molts again and this continues throughout the summer and autumn.

Animals grow quickly, becoming more and more similar to their parents with each molt. For the first 5-7 years, crabs live in one place and only then begin to migrate. At the eighth year of life, female crabs become sexually mature, and at 10 years old, males are also ready to reproduce. Kamchatka crab lives for a very long time - about 15-20 years.

Crab is not only valuable fur delicious food, that's also amazing creature, leading a rather secretive lifestyle. Taste qualities crabs have made them a tasty catch in many countries, and some of their species are on the brink of extinction, partly due to the destruction of coral reefs caused by global warming.

There are more than 4,500 species of crabs on Earth. Outwardly, they may be completely different, but all representatives of the order have eight legs and two claws.
The leg span of the Japanese spider crab reaches 4 meters - thus, its limbs are almost 5 times longer than the legs of an average person. These crabs weigh up to 19 kilograms and live up to 50 years.
The smallest crab in the world is the pea crab, whose body size reaches only a few millimeters.
To attract females, crabs perform intricate dances, during which they tap their claws and rattle their shells.
The body of most crabs is flat, which allows them to climb even into the narrowest crevices.
People started eating crabs back in prehistoric times. Now seafood lovers around the world eat about one and a half million tons of crabs a year.
Crab meat is rich in proteins, making it an extremely nutritious food. In addition, it contains vitamin B12 and anti-inflammatory substances.
Crab meat is recommended to be eaten to prevent heart disease and reduce blood pressure.
The distance between the claws of the record-breaking largest crab ever caught exceeded the height of the crab itself. tall man in the world.
It is known that decapod crustaceans, that is, crabs, lived on Earth during the Jurassic period.
A crab's shell is its external skeleton. Spiders and some types of insects have a similar body structure (see).
The crab's shell does not grow with it, so the animals are forced to molt periodically - shed the old shell and grow a new one. In a one-year-old crab this happens 6 or 7 times, and in adult crabs - once or twice a year.
Due to predators or a fight with another individual, the crab may lose a limb, but it will soon grow back. These creatures can regrow lost body parts just like they do starfish ().
Crabs have adapted to life in almost any conditions: in icy waters off the coast of Antarctica, boiling geysers on the ocean floor, on rocks far from the water and even in tree hollows.
Some crabs protect themselves by placing an anemone on their shell - it camouflages the host animal well and stings predators sneaking up on it.
Crabs, like fish, get oxygen from water, but can stay on land for a long time - the main thing is that their gills do not dry out completely during this time.
Crab teeth are found in their stomach.
40% of a crab's weight is meat.
There is a legend according to which crabs once made a pact with insects. The first people inhabited the water, and the second took dominion over the air.

Seahorses

Seahorses are the only animals in the entire kingdom in which a man, rather than a woman, gives birth and cares for its young!

The females lay their eggs in the male's small pouch, like a kangaroo (pictured right). The male then releases sperm into the water and swims through this cloud to fertilize the eggs in the pouch. Contrary to popular belief, the eggs are fertilized in his pouch. In a pouch on the male's belly, the cubs develop until they can emerge. Pregnancy lasts from two to four weeks.
During pregnancy seahorses meet for about 5-10 minutes, then the female leaves the male. At one time, from 5 to 1500 cubs can be born.

Seahorses are believed to be monogamous and mate for life. However, thanks to recent observations, this theory has been refuted.

The appetite of seahorses is enormous. These sea creatures spend the whole day searching for food. One individual eats about 3,000 brine shrimp per day; the diet also includes small crustaceans and plankton.

sea turtles

Turtles live on every continent except Antarctica.

Sea turtles excrete salts absorbed with food into sea water through the eyes. This is why people think turtles cry.

The smallest turtle in the world is the size of a lid from plastic bottle. Musk land turtles do not exceed 8 centimeters in length and weigh no more than 250 grams.

The most big turtle in the world – leathery (shown in the photo). Its length can reach 2.1 meters, and its flipper span is about 2 meters. The record holder is a male leatherback turtle, which was 2.9 meters long, 2.7 meters wide, and weighed about a ton.

Interesting facts about crabs

Crabs are very aggressive towards each other. Males often fight for the right to possess a female.

Crabs become capable of reproduction at the age of 8-10 years.

How do crabs reproduce? The male attaches his sperm, covered with a water-insoluble coating, to the female's abdomen. Afterwards, the female lays eggs and attaches them to the lower part of the body, under a special protective plate, where they mix with sperm and fertilization occurs. After an incubation period of approximately 11.5-12 months, the hatched crab larvae fall to the bottom. During the growth process, the larva molts up to 5 times. She becomes more or less crab-like at the age of three.

The crab's teeth are in the stomach.

A person walks relying on his hard skeleton, but a crab has an external skeleton, and inside there are only internal organs and muscles.

Forty percent of the crab's weight is meat.

If a crab loses a claw, it can grow a new one. True, it will be smaller in size and will not be as beautiful as the first one.

The Japanese spider crab (pictured left) is the oldest species of crab in the world and is also believed to be the deepest-diving one.
Moreover, it has the longest life expectancy - 50 years.

It is believed that this species prefers to live at a depth of 200-300 meters, but there have been individuals that feel good at depths of 800 meters and above.
About 8.1 million tons of crabs are eaten annually in restaurants and homes around the world, given such a long breeding period, this species of crab is in danger of extinction.