Blue crab value in nature. Blue American occupant crabs survive our Black Sea crabs in Crimea

Blue crab (in Latin - Callinectes sapidus) belongs to the crustacean class.

Description of the appearance of the blue crab.

The blue crab is easily recognizable by the color of the cephalothorax, the color is usually bright blue. The rest of the body is olive brown. The fifth pair of limbs is paddle-shaped and adapted for movement in water. The female has a wide triangular or rounded carapace and red patches on the claws, while the male has a cephalothorax shaped like an inverted "T". The blue crab can have a carapace length of up to 25 cm, with a carapace about twice as wide. Especially rapid growth occurs during the first summer, from 70-100 mm. In the second year of life, the blue crab has a shell 120-170 mm long. The size of an adult crab is reached after 18 - 20 molts.

Distribution of blue crab.

The blue crab spreads from the western part Atlantic Ocean, from Nova Scotia to Argentina. Accidentally or intentionally, this species has been introduced to Asia and Europe. It also lives in Hawaii and Japan. It is found in Uruguay, as well as further north, including Massachusetts Bay.

Habitat of the blue crab.

The blue crab inhabits various places habitats, ranging from the salty waters of sea bays to almost fresh water in closed bays. Especially often settles in the mouths of rivers with fresh water, and lives on the shelf. The blue crab's habitat extends from the lower tide line to a depth of 36 meters. Females remain in water with high salinity in estuaries, especially during the spawning period. In the cold season, when the water temperature becomes lower, blue crabs migrate to deeper waters.

Reproduction of the blue crab.

The timing of the reproduction of blue crabs depends on the region where they live. The spawning period lasts from December to October. Unlike males, females mate only once in their lives, after puberty or terminal molting. Females attract males by releasing pheromones. Males compete for females and protect them from other males.

Blue crabs are very prolific, with females laying between 2 and 8 million eggs per spawn. When females are still covered with a soft shell immediately after molting, males mate and spermatozoa are stored in females from 2 to 9 months. The males then guard the female until the new chitinous cover hardens. When the females are ready to spawn, the eggs are fertilized with stored sperm and placed on tiny adnexal hairs on the abdomen.

This formation is called a "sponge" or "berry". The incubation time for blue crab eggs is 14-17 days. During this period, females migrate to the mouths of estuaries so that the larvae enter the water with high salinity. Blue crab larvae develop at a salinity of at least 20 PPT; below this threshold, the offspring do not survive. The emergence of larvae often occurs at the peak of the tide. Blue crab larvae are carried by water closer to the shore, and their development is completed in coastal shelf waters. The whole cycle of transformations lasts from thirty to fifty days. The larvae then return and inhabit the estuaries, where they eventually develop into adult crabs. The larvae go through eight stages of metamorphosis over a period of about two months before they begin to resemble adult crabs. Males, as a rule, do not protect their offspring, females protect the eggs until the larvae appear, but do not care about the offspring in the future. The larvae immediately fall into environment, so most of them will die before reaching the adult stage.

Usually only one or two crabs survive and can reproduce, and they stay in their environment for up to three years. Many of them become prey to predators and humans before they grow up.

Blue crab behavior.

The blue crab is an aggressive animal, except during periods of molting, when the carapace is still soft. At this time, he is especially vulnerable. The crab burrows into the sand to hide from predators. In the water, he feels relatively safe and actively swims. His last pair walking legs adapted for swimming. The blue crab also has three pairs of walking legs, as well as powerful claws. This species is very mobile, the total distance traveled in a day is about 215 meters.

The blue crab is more active during the day than in the evening. It travels about 140 meters per day, with average speed 15.5 meters per hour.

The blue crab regenerates limbs lost during combat or defense against attack. AT aquatic environment the blue crab is guided by the organs of sight and smell. Marine animals respond to chemical cues and sense pheromones, allowing them to quickly assess potential mating partners from a safe distance. Blue crabs also use color vision and recognize females by the characteristic red color of their claws.

Blue crab food.

Blue crabs eat a variety of foods. They eat shellfish, prefer oysters and mussels, fish, annelids, algae, and almost any plant or animal remains. They eat dead animals, but do not eat decayed carrion for a long time. Blue crabs sometimes attack young crabs.

Ecosystem role of the blue crab.

Blue crabs are hunted by Atlantic croakers, herons, sea ​​turtles. They are also an important link in the food chain, being both predators and prey.

The meaning of the blue crab.

Blue crabs are an object of fishing. The meat of these crustaceans is quite tasty and is prepared in several ways. The crabs are caught in traps that are rectangular, two feet wide and made of wire. They are attracted to bait from fresh dead fish. In some places, crabs are also caught in trawls and donks. Many people eat crab meat, as it is not at all an expensive food product in countries located on the coast.

The conservation status of the blue crab.

The blue crab is a fairly common type of crustacean. It does not experience any special threats to its population, therefore, conservation measures are not applied to it.

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The stone crab is the most aggressive and strongest in underwater world. It can be observed in rocky shallow water. The stone crab is not satisfied with the remains of dead animals. He can grab the careless, easily cracks down on rapans and hermit crabs. With strong claws, he clicks hard shells, like seeds.

The largest crabs live at depth. They often fight over territory and tear off each other's claws. Instead of limbs lost in battle, they grow new ones, only smaller.

Female crabs carry their eggs under their abdomens, which is why females have a wider abdomen than males. This is necessary to protect offspring. Surprisingly, after the larvae hatch from the eggs, they remain under the protection of the mother while they turn into an independent larva - a zoea with a long horn on its head. Zoea lives in plankton, grows up and turns into a larva - a megalope with huge eyes, and only then into a small crab.

The female of the lilac water crab bears lilac caviar. The marbled crab has black caviar. These crabs are inhabitants of the rocky bottom. But swimming crab carries a bunch of bright orange caviar under its belly. He successfully hides on the sandy bottom.

Crabs have excellent defenses - strong claws and a shell as hard as armor. But in order to grow up, the crab must change the old shell for a new one. It's time for shedding. To get rid of the old armor, the crab fills with water, swells, and its shell bursts. The crab literally flows out of the shell and hides his soft translucent body in a secluded place. He needs to sit out for several days until the new soft shell hardens. At this time, the crab has time to grow.

The long legs of the marble crab are covered with hairs. He runs very fast this is the only one of the Black Sea crabs running out of the water. Due to this similarity, the marble crab is often called the spider crab. marble crabs live in rocky shallow water and prey on small fish and shrimps. Their claws have sharp cutting edges.

Is it true that the flowerbed walk?

Yes, it's true if you planted this flower bed and grew it on yourself invisible crab! It is impossible to notice him under water among the thickets: the gardening crab is a master of disguise. It hides among algae and mainly feeds on them.

blue crab- the rarest of all crabs living in the Black Sea. It got its name due to its color: claws and the ends of its paws are blue-turquoise. The shell of the blue crab is decorated with spikes, its width reaches 30 centimeters. Unfortunately, meeting a blue crab underwater is a rarity. This crab appeared in the Black Sea half a century ago from a warm mediterranean sea, and the birthplace of the blue crab is the East Coast of the United States. The Black Sea turned out to be too cold in winter for blue crab juveniles, so it never managed to breed much. Sometimes he still gets into the nets of fishermen. The blue crab can be seen in marine aquarium in Anapa.

Funny pea crab often visits with his friends -. And sometimes he becomes a temporary tenant, climbing into the shell of a living mussel. Perhaps this is how he hides from predatory fish. This crab has a body no larger than a pea, but the claws are quite long. Pea Crab - the smallest crab Black Sea.

This handsome man on the territory of our vast Motherland can only be found in the Black Sea. The blue swimming crab is an immigrant. He came to us from the east coast of the United States.

The blue swimming crab has an average size. The shell reaches a width of 10-20 centimeters and forms a trapezoid in the back. Along the edges are sharp spikes that serve as an excellent defense against many predators, but not from humans. The claws are relatively thin and long. Males are distinguished from females by a narrower shell on the abdomen.

Unlike land crabs, swimmers have flattened hind legs and resemble flippers. This makes them excellent swimmers.

The main color of the crab is brown, but the sides of the shell and legs with claws are painted in Blue colour. For such an unusual color, the crab owes special pigments.

Its natural enemies are eels, sea ​​bass, some species of sharks, trout and others Marine life. The crabs themselves are omnivores. They can eat both animal and plant foods: bivalves, fish, annelids, algae and carrion.

Their breeding season is November-December. After mating, the female can store the male's sperm for about a year and fertilize the eggs at the right time for her. 4-5 weeks after fertilization, small crabs appear from the eggs, which are already left to themselves. Most of them become prey for fish and other crustaceans.

The blue crab is an immigrant. Until the 60s of the 20th century, it was not observed in the waters of the Black Sea. This crab is native to the East Coast of the United States. From there, in the early 1960s, together with the ballast water of ships, it first entered the Mediterranean Sea, and from there to us. In the same way he travels all over the world. So now it can be found in the waters of Nova Scotia and Argentina.

For half a century of living in the Black Sea, its population has not grown much. Still, he's used to more warm waters and our 5-7 from the water in winter time were too low for him.

In many countries of the world, blue crab meat is rarely eaten, as it is difficult to cook deliciously. But for Americans, this is not a problem. An extensive fishery for this crustacean is carried out in the state of Maryland. But, despite this, blue crab meat is not enough for everyone, so it is considered a delicacy.

The original homeland of the blue crab is the Atlantic coast of North and South America. In Europe, this species was first discovered in 1900. Today it can be found in the vast territories of the Baltic and North seas. It is also found in the Mediterranean and Adriatic seas.

The blue crab lives mainly in the mouths of rivers and in shallow water at a depth of up to 36 m, deeper in winter. It prefers muddy and sandy bottoms.

Young crabs need a water temperature of 15 to 30 °C. Adult animals can tolerate water temperatures up to 10 °C. Larvae, in contrast to young and adult animals, are demanding on the average salinity value, not tolerating values ​​below 20 percent.

Description

The blue crab carapace reaches a width of 17.8-20 cm and a length of 7.5-10.2 cm. Males are larger than females. The weight of sexually mature animals ranges from 0.45 to 0.90 kg. The dorsal carapace is dark brown, grayish, greenish or bluish-green in color and has orange spines up to 8 cm wide on each side. lower limbs and belly are whitish.

Claws have different color shades depending on gender. Pincer tips are bluish in males and reddish in females.

The blue crab has five pairs of thoracic limbs. The front pair of limbs is transformed into two strong claws of different sizes. The massive crushing claw is used to split shells, while with the help of a smaller claw, the crab tears soft tissues and sends food to the mouth opening. The fifth pair of limbs is similar in shape to a kayak paddle and is used for swimming. Blue crabs are able to throw off their claws in case of danger. The crab can then regenerate the lost limbs.

Compound eyes on short stalks located directly under the anterior margin of the carapace on the head. Between the eyes are two pairs of short and thin antennae.

The lifespan of a blue crab is approximately 2 to 4 years.

Lifestyle

After mating, the females return to the shallow waters. salt water, while the males remain in the estuaries.

Most of the time, crabs hide in the mud or sea ​​grass to spy on your prey or protect yourself from enemies. The blue crab is quite aggressive compared to other species.

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Useful information

Blue crab (lat. Callinectes sapidus)

Food

The blue crab competes with other crustaceans for food. This is an omnivore. Its dietary spectrum includes shellfish such as mussels, young crustaceans, fish, worms, and plants. Does not disdain to eat carrion. With a lack of food, the animal is prone to cannibalism.

natural enemies

To natural enemies blue crab includes red croaker, common croaker, American herring gull, different kinds herons, and sea turtles.

The blue crab is considered a delicacy and is caught in large numbers.

Reproduction and development

The blue crab becomes sexually mature at 12 to 18 months of age. Females mate only once a year, immediately after the molt, while males mate more frequently.

Like all crustaceans, the blue crab sheds periodically throughout its life. After molting, the female carapace is soft for a short time. The female spawns about 2 months after mating. The clutch consists of 2 million eggs. Spawning begins in December and ends in October.

The incubation period is approximately 14 days. Within 2 months, planktonic larvae go through 8 stages before they acquire the appearance of crabs.

Description

• sea ​​acorns (Balanidae)
• other barnacles (Cirripedia)
• nematodes (Nematoda)
• trematodes (Trematoda)

Reproduction and development

The blue crab becomes sexually mature at 12 to 18 months of age. Females mate only once a year, immediately after the molt, while males mate more frequently.

Like all crustaceans, the blue crab sheds periodically throughout its life. After molting, the female carapace is soft for a short time. The male uses this time to mate with the female. The female is quite capable for a long time store male sperm.

The female spawns approximately 2-9 months after mating. The clutch consists of 2 million eggs. Spawning begins in December and ends in October, with a peak in spring and summer. After the female has laid her eggs, the eggs are fertilized with stored sperm and attached to tiny hairs on her ventral legs.

The incubation period is approximately 14 days. Within 2 months, planktonic larvae go through 8 stages before they acquire the appearance of crabs.

Notes

Literature

• Diverse: Grzimeks Tierleben. Niedere Tiere. 1.Bd. Deutscher Taschenbuch Verlag GmbH & Co.KG, München Oktober 1993
• Hans-Echhard Gruner, Hans-Joachim Hannemann und Gerhard Hartwich, Urania Tierreich, 7 Bde., Wirbellose Tiere, Urania, Freiburg, 1994

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See what the "Blue Crab" is in other dictionaries:

- "Tintin on Far East"(Fr. Les aventures de Tintin, reporter, en Extrême Orient) or" Blue Lotus "(Le Lotus bleu)" Hergé's fifth album of classic comics about the adventures of Tintin (1936). Continuation of "Pharaoh's Cigars", the action of which ... Wikipedia