Black sea marble crab. The sea spider is not a spider at all, but a crab. Security Notes

Area

Distributed in the northeastern Atlantic (from the coast of Britain to Morocco), in the Mediterranean, Aegean, Marmara and Black Seas.

Features of morphology

Body color is dominated by brown tones with a characteristic light pattern, similar to a marble pattern. The claws are often red-brown with lighter tips. In young individuals, the carapace and the surface of the pereopods (walking legs) are dark brown with a purple tint. The body shape is quadrangular. The width of the carapace is slightly longer. The surface is flat, with clearly visible short transverse strokes. On each side of the carapace there are three well-developed teeth. The walking legs are long and abundantly covered with hairs. Length – up to 40 mm, width – up to 45 mm.

Features of biology

goes ashore. In the period from June to November it concentrates in the area near the water's edge. It is found mainly on coastal cliffs and stones, preferring hard soils with aquatic vegetation. It feeds on bottom invertebrates, algae and organic debris. Larvae are found from July to August. The complete development cycle includes four zoea stages and one megalop stage.

Threats

Seizure for commercial purposes for making souvenirs and amateur catching for fun.

Security measures

Guarded in nature reserves: "Cape Martyan" and Karadagsky, national natural park"Tarkhankutsky" and other protected areas. There is a need to strengthen outreach efforts among local population and vacationers about the role of crabs in marine biocenoses.

Information sources

Kobyakova, Dolgopolskaya, 1969; Makarov, 2004; Katsanevakis et al., 2007.

Compiled by: Statkevich S. V. Photo: Karpova E. P.

Sea spiders, also known as spider crabs, also known as marble crabs, live in the Mediterranean, Black Sea and Atlantic Ocean, near the coasts of Morocco and France. They are found on the Crimean peninsula and the Caucasus coast, at shallow depths with a rocky or rocky bottom.

Sea spiders are members of the Grapsidae family. These crabs are called "spider" crabs because of their long, dark legs, and they get the name "marble" because of the characteristic pattern on their shell.

Description of the sea spider

The spider crab is small and agile, its body length reaches only 38 millimeters and its width is 43 millimeters. The carapace is square and flat. The anterior edge, located between the eyes, is especially wide and straight, with 3 sharp teeth on each side. Top part the shell can become overgrown with small crustaceans called balanuses, as well as algae.

The skeleton is external, respiration is carried out using gills. The left claw has small teeth that tightly close together. The right claw is larger than the left, the teeth are curved, and there is a gap between them. Externally, the right claw resembles forceps. The marble crab is a decapod crustacean, has 10 long, strong legs, covered with hairs. The color of the shell ranges from brownish-greenish to brownish-violet. The shell is decorated with a wavy pattern reminiscent of marble.

Spider crab lifestyle

Sea spiders live in the coastal zone; they stay at the very edge of the water and can even leave the water at a distance of up to 5 meters. This is the only Black Sea crab that can run out of the water. In the sea they can live at depths of up to 10 meters.

Marble crabs tolerate drying out well and love to bask on rocks in the sun. Spider crabs build their own homes. The crab selects a stone and begins to climb under it, throwing grains of sand out from under the stone with its claws; the crab hides in the resulting niche. Having accumulated reserves and having eaten well, the sea spider hides in a safe shelter.

Sea spiders feed on the remains of plants and animals, plankton, mollusks and polychaetes. They climb onto rocks protruding from the water and clean their surface. In case of any danger, the crab instantly hides in any crevice, and if there is none, it rushes into the water.

At night, he carefully crawls out of his old shell. At night they can climb onto rocks to a height of 3-5 m. They cannot burrow into the sand, but they are perfectly camouflaged among algae and mussels. If a crab loses a leg or claw, the lost organ is restored after 2-3 molts. The lifespan of a spider crab is 3 years.

Reproduction of marble crabs

The breeding season for sea spiders occurs in July-August at a water temperature of about 17 degrees.

One female lays up to 87 thousand eggs. Incubation lasts 25 days. Crab larvae eat plankton. Metamorphosis takes place in 4 stages. Puberty in females occurs at 2 years.

Marble crab population

Like other Black Sea crabs, sea spiders are used to make souvenirs, but they are not a commercial species.

Spider crabs are included in the Red Book of Ukraine, because Lately their numbers decreased sharply. These crabs are protected in the Karadagsky and Cape Martyan natural reserves.

Closest relatives of spider crabs

There are more than 10 thousand species of decapod crabs with five pairs of legs and bulging, stalked eyes. For example:
Stone crabs are the most large crabs at the Black Sea. The width of the stone crab's shell is about 10 centimeters. They prefer to live deeper, but can be found close to the shore;
The hairy crab looks like a stone crab, but is smaller in size, and its carapace is covered with numerous yellowish hairy bristles. They live closer to the shore, under the rocks;
Mediterranean or grass crabs have a green shell, which is why they are called “grass crabs.” Grass crabs are shallow water dwellers;
Water crab or lilac crab. It is slower and prefers to live exclusively in shallow water;

The swimming crab loves to burrow into the ground. Its small hind legs look like blades; with their help, the crab throws sand on itself. The crab also uses these legs for swimming; the swimming crab is the only one among the Black Sea crabs that can swim;
Blue crab came to the Black Sea from the Mediterranean in the 60s. He arrived in our latitudes with the ballast waters of ships. But the Black Sea water is too cold for young blue crabs, so they are extremely rare;
The invisible crab got its name because it is almost impossible to notice it in algae. These long-legged and skinny sea ​​creatures they know how to camouflage themselves perfectly;
The Pea Crab typically lives among the mussels and can sometimes even crawl inside the shell. It is extremely difficult to see this crab, since an adult is no larger than a ten-kopeck coin;
Freshwater crab- an unusual Crimean crab. It differs not in size, but in origin and lifestyle. From the name it is clear that it lives in fresh water: V mountain rivers and ponds.

Freshwater crabs cannot be spread by currents, so they must travel on land at night. They once crossed the entire continent on foot in this way; it is believed that they originated in South-East Asia.

Keeping marble crabs in an aquarium

Sea spiders do not dig holes, they prefer to hide under stones, so the bottom of the terrarium is covered with pebbles or sand, and there should be a variety of shelters at the bottom, for example, driftwood, stones, and ceramics. To make the aquaterrarium look more beautiful, it can be enlivened with the help of plants.

Description:

Marble Crab (Spider Crab, Spider Crab, sea ​​spider) - Pachygrapsus marmoratus is the only Black Sea crab that runs out of the water onto coastal stones and rocks. It is a member of the Grapsidae family. The marble crab received its common name due to the moire pattern on its shell, which resembles noble marble. Marble crabs are also often called “spider crabs” due to their dark color and long legs.

The shape of the Sea Spider's shell is trapezoidal. The marble crab is small in size. Basically, the cephalothorax of an adult reaches a width of 45-50 mm. The maximum size is 6 centimeters. Top surface The flat carapace is sometimes overgrown with balanuses (small crustaceans) and algae.

The Marble Crab, like other representatives of the decapod crustacean genus, has ten strong and long legs. The two front legs are turned into claws. The walking legs of the Spider Crab are abundantly covered with hairs.

The marble crab has a blue-green to dark brown shell with many colors light stripes.

The sea spider is mainly found in shallow water among stones in the surf zone. In the sea, the crab lives at a depth of up to 10 meters. The marble crab can survive without water for some time, so it freely comes to land. But at the first danger, the Spider Crab instantly rushes into the water or hides in the nearest crack. During daylight hours, marble crabs hide under big stones, and at night they leave the sea and make trips to the shore. Under cover of night, these brave crabs can climb rocks to a height of 2-5 meters above sea level.

IN natural environment The marbled crab feeds on bottom invertebrates and organic debris.

The marble crab, like other Black Sea crabs, is used for the production of souvenirs and for food, but it has never been a commercial species.

The lifespan of a marbled crab in natural conditions is 3-3.5 years. The marble crab is listed in the Red Book of Ukraine, as its numbers have recently decreased significantly. The spider crab is protected in the Ukrainian nature reserves Cape Martyan and Karadag.

Habitat:

The habitat of the marbled crab covers the Black, Azov and Mediterranean Sea, Atlantic Ocean from the North-West coast of France to the Azores. The marble crab is found on the coast of the Caucasus and Crimean peninsula at shallow depths with a rocky or rocky bottom.

WITH possession in an aquarium:

The marble crab is kept in a marine aquaterrarium, where the water salinity is 17-33% (desalinated water leads to the rapid death of the animal). The ratio of the sizes of the reservoir and land is 1:3, which is optimal.

The depth of the reservoir in the aquaterrarium should be 5-15 cm. The Spider Crab does not dig burrows; it prefers to hide under stones, so on the pebble or sandy bottom of the aquarium there should be many different shelters (stones, driftwood, ceramics). The aquaterrarium can be landscaped with living plants.

The water in the aquarium should be hard and its temperature should not exceed 25°C. Once a week it is necessary to replace 25% of the water with fresh water. Good filtration and aeration are also very important.

Marble crabs are unpretentious in nutrition. Diet of a sea spider in an aquarium includes bloodworms, tubifex, finely chopped vegetables, fruits and seafood (fish meat, shrimp).

• Crabs

Names: marble crab, spider crab, sea spider.

Area: Black and Mediterranean seas, Atlantic Ocean (coast of France and Morocco).

Description: marble crab is small, agile, with a flat, square shell (size 3.5x4.5 cm). The edge of the front side between the eyes is particularly straight and wide with three sharp teeth on each side. Breathes through gills. External skeleton. Left claw, with small, tightly closed teeth. The right claw, larger, with curved teeth and a gap in the middle, looks like forceps. The crab's legs are long and covered with hairs.

Color: the shell is greenish-brown to violet-brown, covered with a wavy pattern similar to marble.

Size: length - 38 mm, width - 43 mm.

Lifespan: 3 years.

Habitat: coastal zone: at the very edge of the water and even outside the water (up to 5 m). The marbled crab lives on rocks, in the cracks of breakwaters, piers or similar places.

Food/food: remains of animals and plants, mollusks, polychaetes, plankton.

Behavior: The marble crab climbs onto stones and rocks protruding from the water and cleans their surfaces. At the slightest danger, it quickly crawls into the nearest crevice, and in its absence, it rushes into the sea. The crab easily tolerates drying out and loves to bask on sunlit rocks. Builds a home. Having chosen a stone, it begins to squeeze under it - pulling out sand and small stones with its claws and pushing out sand and small stones with its paws, the marble crab hides in the resulting niche. Having fed well and accumulated nutritional reserves, it hides in a safe shelter. At night, he carefully climbs out of his old shell. Lost legs and the claws are restored after two or three molts. The marble crab is perfectly camouflaged among mussels and algae. Doesn't know how to bury itself in sand.

Reproduction: one female can lay up to 87 thousand eggs.

Breeding season/period: July-August (at a water temperature of 17"C).

Puberty: females mature at 2 years.

Pregnancy/incubation: 25 days.

Offspring: Crab larvae feed on plankton. Metamorphosis with 4 stages.

Population/Conservation Status: The marbled crab is included in the Red Book of Ukraine.

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On the Black Sea coast, wherever there is large stones, you can meet crabs. Moreover, you can’t even imagine how much the shore and shallow waters are teeming with these crustaceans. During the day you can see several small crabs swarming on the rocky algae at the very edge of the water. But as soon as they notice any movement within a radius of several meters, they disappear in all directions. And, of course, the time of reign for crabs is twilight, here they appear in thousands. Where do the crabs hide the rest of the time? The best shelters for them are cracks and crevices between stones, where they squeeze through, and backwards. So that curious eyes on stalks and powerful claws look out - try to pick it out from there. The pictures below show mostly marble crab (Pachygrapsus marmoratus). In Omega Bay in Sevastopol, swimming with a mask between the rocks, I easily found their shelters under water. It is enough to look into any crack between the stones to see in its depths glittering eyes on stalks and threatening claws. True, it was dark and cloudy there, so I had to use a flash.

marble crab(lat. Pachygrapsus marmoratus) - a type of crab, got its name because of the characteristic pattern - dark wavy lines on the shell. Other names: spider crab, sea spider. In behavior it really resembles many spiders. The local name on the southeastern coast of Crimea is Gypsy.

The marble crab has a blue-green to dark brown shell, mottled with many light stripes, reminiscent of variegated marble. Because of its dark color and long legs, it is often called the spider crab.

This is the only Black Sea crab that runs out of the water and travels along coastal stones and rocks. At night, they can climb 2-5 m up rocks, and on gentle slopes move 5-10 m away from the water’s edge. However, at the first danger, they instantly take off and throw themselves into the water or the nearest crevice.

The shape of the sea spider's shell is trapezoidal. The marble crab is small in size. Basically, the cephalothorax of an adult reaches a width of 45-50 mm. The maximum size is 6 centimeters. The upper surface of the flat carapace is sometimes overgrown with balanuses (small crustaceans) and algae. The marble crab, like other representatives of the genus decapod crustaceans, has ten strong and long legs. The two front legs are turned into claws. The walking legs of the Spider Crab are abundantly covered with hairs.

Life expectancy: 3 years. Habitat: coastal zone: at the very edge of the water and even outside the water (up to 5 m). The marbled crab lives on rocks, in the cracks of breakwaters, piers or similar places.

The marble crab climbs onto stones and rocks protruding from the water and cleans their surfaces. At the slightest danger, it quickly crawls into the nearest crevice, and in its absence, it rushes into the sea. The crab easily tolerates drying out and loves to bask on sunlit rocks.

Builds a home. Having chosen a stone, it begins to squeeze under it - pulling out sand and small stones with its claws and pushing out sand and small stones with its paws, the marble crab hides in the resulting niche. Having fed well and accumulated nutritional reserves, it hides in a safe shelter. At night, he carefully climbs out of his old shell. Lost legs and claws are restored after two or three molts. The marble crab is perfectly camouflaged among mussels and algae. Doesn't know how to bury itself in sand.

The habitat of the marbled crab covers the Black, Azov and Mediterranean seas, the Atlantic Ocean from the North-West coast of France to the Azores. The marble crab is found on the coast of the Caucasus and the Crimean Peninsula at shallow depths with a rocky or stony bottom.

And in the last two photos there is a different type of crab - Stone crab(lat. Eriphia verrucosa). Stone crab is the most big crab in the Black Sea. The width of its shell is 9-10 cm. It prefers to live deeper, although it is often found close to the shore, but this is only in deserted rocky places.

If all bottom crustaceans are primarily scavengers (by the nature of their diet), then the stone crab, strong and aggressive, can be a fast and dexterous predator. In ambush he lies in wait for snails, worms and small fish. Its claws have monstrous strength - they snap like seeds, shells of mollusks and hermit crabs. Their muscle fibers at the molecular level differ from those of animals and humans (not in our favor).

The color of the stone crab's shell is always the same as that of the stones among which it lives. Basically, it is a red-brown color, but stone crabs living among yellow sandstones are themselves quite light.