Callinectes sapidus is preyed on by the red drum, Atlantic croaker, herons, sea turtles and humans. They are also an important link in the food chain, being both predator and prey. They feed on fish, aquatic vegetation, mollusks, crustaceans, and annelids.
Known Predators:
Callinectes sapidus is easily identified by its body color which is generally a bright blue along the frontal area, especially along the chelipeds (the appendages bearing a "chela" or pincher-like claw). The remainder of the body is shaded an olive brown color. To accommodate swimming, the fifth leg is adapted to a paddle-like shape, as is the same with other portunids. Females have broad triangular or rounded aprons and red fingers on the chelae, whereas in the male the abdominal flap, or apron, is shaped like an inverted "T". Callinectes sapidus can grow to 25 cm in carapace length (CL), with carapace width being approximately twice the length. Growth is rapid during the first summer, with crabs growing from 70-100 mm CL. By the second year, maturity is reached at carapace lengths of 120-170 mm. Callinectes sapidus grows to adult size after 18 to 20 molts.
Range length: 120 to 170 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
Callinectes sapidus has an average life span of 1-2 years. Many are harvested by humans before they would die naturally. In the St. Johns River, some blue crabs survive to four years of age.
Range lifespan
Status: wild: 1 to 4 years.
Average lifespan
Status: wild: 2 years.
Typical lifespan
Status: wild: 1 to 2 years.
Callinectes sapidus, the blue crab, is a bottom-dweller found in a variety of habitats ranging from the saltiest water of the gulf to almost fresh water of the back bays. Especially common in estuaries, this species ranges into fresh water, and may be found offshore. The blue crab's habitat ranges from the low tide line to waters 120 feet (36 m) deep. Females remain in higher salinity portions of an estuary system, especially for egg laying. During times of the year when temperatures are colder, C. sapidus tends to migrate to deeper water.
Range depth: 1 to 36 m.
Habitat Regions: temperate ; tropical ; saltwater or marine ; freshwater
Other Habitat Features: estuarine
Although the natural range of Callinectes sapidus spreads from the western Atlantic Ocean from Nova Scotia to Argentina, it was introduced, accidentally or deliberately, into both Asia and Europe. It has also been introduced into Hawaii and Japan. Callinectes sapidus is mostly found from Cape Cod (Massachussets) to Uruguay, but is also found north to at least Massachusetts Bay.
Biogeographic Regions: nearctic (Native ); palearctic (Introduced ); ethiopian (Introduced ); neotropical (Native )
Callinectes sapidus eats a large range of foods. Typically this species eats clams, oysters, and mussels as well as almost any vegetable or animal matter. This species will scavenge freshly dead animals but not long dead animals. The crabs will sometimes also eat young crabs.
Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans; other marine invertebrates
Plant Foods: leaves
Primary Diet: carnivore (Piscivore , Vermivore, Eats other marine invertebrates, Scavenger ); herbivore (Folivore , Algivore); omnivore
Parasites are very common on Callinectes sapidus. Barnacles, worms and leeches attach themselves to the outer shell; small animals called isopods live in the gills or on the abdomen; and small worms live in the muscles. Although C. sapidus is a host to many parasites, most of these do not affect the life of the crab.
Commensal/Parasitic Species:
The main positive economic importance of Callinectes sapidus for humans is for food. The blue crab is often eaten because the meat is tasty and can be prepared in a number of ways. Commercially, crabs are captured in traps that are rectangular, two feet wide, and are made of wire. The crabs are lured in by being baited with freshly dead fish. In some areas, crabs are also caught in trawls and by trotlines. Many people also crab since it is easy and inexpensive. Although there aren't any harvest limits, there is a 5-inch minimum body width as measured from spine to spine.
Positive Impacts: food
There are no known adverse effects of Callinectes sapidus on humans.
Callinectes sapidus usually goes through seven zoeal stages and 1 postlarval, or megalopal stage. Sometimes an eighth zoeal stage is observed. Larval abundance is greatest when the tide begins to recede, because the larval release often occurs at the peak of high tide. Blue crab larvae are advected offshore, completing development in coastal shelf waters. Typical development through the seven zoeal stages is between thirty and fifty days before metamorphosis to the megalopal stage. The megalopa persists between six and fifty-eight days. The megalopal stage returns to estuaries for settlement, and eventual recruitment to adult populations.
Development - Life Cycle: metamorphosis
Callinectes sapidus is not listed by any conservation programs.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Callinectes sapidus is both colorful and highly visually responsive, yet almost all studies of their courtship have focused on chemical cues. In the underwater environment of C. sapidus, visual cues may function more rapidly and over a longer distance than chemical cues. Given that C. sapidus is aggressive and cannibalistic, visual cues may allow them to quickly evaluate potential mates from safer distances. The crabs will use color vision and color in mate choice with males having a preference for females with red claw dactyls.
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; chemical
Spawning peaks in Callinectes sapidus are closely associated with the region they inhabit. Unlike males, female C. sapidus mate only once in their lifetime, after the pubertal or terminal molt. When approaching this final molt, females attract males by releasing a pheromone in their urine. Male crabs compete for females and until molting occurs they will protect them. At this time mating occurs, and may last as long as 5-12 hours.
Mating System: polygynous
Callinectes sapidus is highly fertile, with females producing from 2 - 8 million eggs per spawn. When females are in their soft-shell stage immediately after molting, the males transfer their sperm to them for storage. The male then protects the female until her new shell hardens. The females will spawn two to nine months after mating, laying up to eight million eggs. Spawning season is from December to October, with a peak both in spring and summer. When females are ready to spawn, they fertilize the eggs with the stored sperm and place them on the tiny hairs of the appendages on their abdomen. The female is called a "sponge" or "berry" crab while she carries eggs like this. The blue crab's incubation time is 14-17 days, which is when the eggs are brooded. During this time females migrate to the mouths of estuaries so that larvae may be released into high salinity waters. Blue crab larvae have a salinity requirement of at least 20 ppt, and show poor survival below this threshold. The megalops (or larvae) pass through eight stages in about two months before they begin to resemble adult crabs. Usually only one or two crabs survive to become adults, and they have a lifespan up to three years.
Breeding interval: Males mate more than once, during each mating season, where females only mate once in their lifetime.
Breeding season: All year, but spawning occurs mostly during the months of December until October.
Range number of offspring: 2 million to 8 million.
Average number of offspring: 1.
Range gestation period: 14 to 17 days.
Average time to independence: 2 months.
Range age at sexual or reproductive maturity (female): 12 to 18 months.
Range age at sexual or reproductive maturity (male): 12 to 18 months.
Key Reproductive Features: year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); broadcast (group) spawning; ovoviviparous
Males tend to stay and protect the female until she has grown her hard shell after molting, but males have no interaction with the young. The female will protect the young while they hatch, but do not have a significant role in parenting. This is because there are so many eggs, and the maturing time is much too long for her to watch over them. They have to be independent from the time they hatch, which is why most of them will die before they reach the adult age.
Parental Investment: pre-fertilization (Protecting: Male); pre-hatching/birth (Provisioning: Female)
Barnacles often attach themselves to Blue Crabs, especially in southern regions. The Striped Barnacle (Balanus amphitrite) and Turtle Barnacle (Chelonibia testudinaria) are found externally; a small goose barnacle, Octolasmus lowei, occurs in the Blue Crab's gill chamber, and the bean-shaped sacculinid barnacle Loxothylacus texanus attaches itself under the abdomen. A parasitic nemertean worm, Carcinonemertes carcinophila, is found on the gills of female crabs; on virgin crabs, it is pinkish, while on breeders it is red. (Gosner 1978)
Feeding experiments carried out by Harding (2003) suggest that the Blue Crab may be an effective predator of the Rapa Whelk (Rapana venosa), a large predatory gastropod from Asia that was discovered in Chesapeake Bay in 1998. Although mature Rapa Whelks are probably too large and well protected to be attacked by Blue Crabs, available data suggest that predation by Blue Crabs on juvenile Rapa Whelks might control whelk populations in Chesapeake Bay and other estuarine habitats along the North American Atlantic coast.
Except when they have recently molted and have still-soft shells, Blue Crabs are very aggressive when threatened, although they will also burrow into sand to hide (Gosner 1978; Pollock 1998).
Baldwin and Johnsen (2009) investigated mate choice in Blue Crabs, carrying out mate choice experiments using males and manipulated photographs of females. Their results indicated that courtship and mate choice behavior in Blue Crabs can be stimulated by visual cues alone. Males showed a preference for females with red claw dactyls ("pincers"). In binary choice experiments, males displayed more often to photographs of females with red claws than to those with white claws or black claws, strongly suggesting that these male crabs made their choices based on the hue of the red claws and, more broadly, that Blue Crabs are capable of color vision and use color in mate choice.
The Blue Crab (Callinectes sapidus) is found from Cape Cod to Uruguay, occurring especially in estuaries. It is a beautifully colored crustacean with bright blue claws--the mature female's claws are tipped in red--and an olive to bluish green carapace. The Blue Crab is a commercially important species and is popular with recreational crabbers as well. (Gosner 1978; Lippson and Lippson 1997). The Greek and Latin roots of its scientific name translate to "savory beautiful swimmer".
The Blue Crab (Callinectes sapidus) is found from Cape Cod to Uruguay, sometimes north at least to Massachusetts Bay (Gosner 1978). Blue Crabs have also been introduced accidentally or intentionally in Hawaii, Europe, Japan, and Africa.
Place et al. (2005) analyzed the complete mitochondrial genome of the Blue Crab.
The Blue Crab (Callinectes sapidus) is especially common in estuaries, where it ranges into fresh water, but may be found offshore to at least 36 meters (Gosner 1978). Females remain in higher salinity portions of an estuary system, especially for egg laying (Lippson and Lippson 1997). Blue Crabs migrate to deeper water in winter (Gosner 1978).
Lippson and Lippson (1997) describe the life cycle of the Blue Crab in Chesapeake Bay, Maryland, U.S.A., which is famous for its Blue Crabs. Blue Crabs spawn near the mouth of the Chesapeake from May to October. The sponge, or egg mass, which may contain up to 2 million eggs, adheres to the undersurface of the crab. The color of the egg mass is golden orange at first, but changes to black as hatching approaches. After a few weeks, small semi-transparent zoae larvae are released. Many of these larvae are swept out into the ocean, where they mix with Blue Crab larvae from other regions of the coast and, eventually, are blown into regional estuaries such as the Delaware and Chesapeake Bays. After additional molts, a second larval form, the megalops, is produced. The megalops, which resembles a tiny lobster, moves along the bottom and up into the Bay system, where it molts into a tiny but recognizable Blue Crab. By 12 to 16 months, the crabs have molted several times and reached sexual maturity at an average size of about 13 cm.
Several other Callinectes species overlap in range with the Blue Crab (C. sapidus). Callinectes similis is quite similar in appearance, but has 6 teeth along the front of the carapace between the eyes (often more technically described as "4 teeth, not counting the inner orbital teeth"), while C. sapidus has just 4 (or 2, not counting the inner orbitals)(Gosner 1978; Pollock 1998). It also reaches a size of only about 125 mm across (vesus 225 mm for C. sapidus). Callinectes similis is a common estuarine crab south of Cape Hatteras, North Carolina (U.S.A.), ranging into fresh water; from Cape May, New Jersey, south to Cape Hatteras it is usually recorded from depths of at least 9 meters or more and salinities of about 15 ppt (Gosner 1978; Pollock 1998). Other Callinectes species in the Atlantic/Caribbean/Gulf of Mexico region also have 6 frontal teeth (4, not counting inner orbitals), although the inner pair may be very reduced.
The last pair of the Blue Crab's legs are paddle-shaped for swimming. The shell is more than twice as wide as long with 9 marginal teeth (the 9th is a strong spine). The shell is usually olive or bluish-green above and the claws are bright blue below (young are paler). The male's abdomen is abruptly tapered, while the female's is more broadly rounded. Adults may reach a width of 225 mm between the tips of the longest spines. (Gosner 1978)
Blue Crabs feed on plants, shellfish, recently dead fish, and a wide variety of other prey they can kill or scavenge, including recently molted soft-shelled individuals of their own species (Lippson and Lippson 1997).
Blue Crabs are the basis for a commercially valuable fishery in many regions, but as with so many other fisheries, overexploitation has been a major problem. The Chesapeake Bay has traditionally been one of North America’s most productive fishing grounds, supporting the world’s largest Blue Crab fishery. However, sustained fishing mortality and environmental deterioration led to an ∼70% decrease in Blue Crab abundance in Chesapeake Bay during the last decade of the 20th century and first few years of the 21st, from an estimated 900 million crabs down to ∼300 million, with 45–55% of those crabs harvested annually. Even more alarming, studied have found that spawning stock abundance and biomass in Chesapeake Bay declined by 81% and 84%, respectively, around this same period. Consequently, the Blue Crab fishery, which in the early 1990s was a 52,000-ton, $72-million industry, declined to a 28,000-ton, $61-million harvest in 2004. A multidisciplinary, multi-institutional program was developed to study the basic biology and life cycle of the Blue Crab, develop hatchery and nursery technologies for mass production of blue crab juveniles, and assess the potential of using cultured juveniles to enhance Blue Crab breeding stocks and, in turn, bay-wide abundance and harvests. Basic biology and culture studies yielded methods to mass produce larvae and juvenile Blue Crabs in captivity. Juvenile crabs have been produced year-round, with excellent survival. During 2002–2006, over 290,000 cultured crabs were tagged and experimentally released into the bay’s nursery habitats. Cultured crabs survived as well as their wild counterparts, increased local populations at release sites by 50–250%, grew quickly to sexual maturity, mated, and migrated from the release sites to spawning grounds, contributing to the breeding stock as soon as 5 to 6 months post-release. (Zohar et al. 2008 and references therein) Despite their enthusiasm and optimism regarding stock replenishment efforts, Zohar et al. (2008) emphasize their view that in addition to mass rearing and releasing of Blue Crab juveniles, successfully restoring Blue Crab populations will require the integration of adequate management strategies to protect the wild and released animals until sexual maturity and spawning, with fishery and seafood industry, policymakers, environmental activists, and scientists all working together.
Paolisso (2007) explored the evolving role of the Blue Crab in the human culture around the Chesapeake Bay watershed.
El cranc blau (Callinectes sapidus) és un crustaci decàpode que presenta cinc parells de potes; el seu cos està cobert d'un exoesquelet de color verd fosc.
En els mascles, les potes (pleòpodes) tenen un color gris-blavós, i és aquesta característica la que els ha donat el nom comú de cranc blau. No obstant això, en les femelles les puntes de les potes són de tonalitat vermellós-ataronjat.
Són espècimens actius i voraços; la seva dieta alimentosa està basada en crustacis, peixos, gran varietat de mol·luscs i algues.
Com la resta dels crustacis són ovípars. Es reprodueixen en aigües properes a les costes a la primavera i estiu. Es calcula que la fecunditat d'una femella de grandària mitjana, és de 700.000 a 2 milions d'ous.
Habiten en costes tropicals i temperades, en aigües de badies, llacunes costaneres, esterus i desembocadures dels rius, a una temperatura entre els 18 i 23 °C, i a les platges a profunditats entre 0,40 i 2 metres. Poden viure entre 3 i 8 anys.
El cranc blau és la especialitat del poble Dalyan en el districte de Ortaca de la província de Muğla, a la Regió de l'Egeu, Turquia.[1][2][3]
El cranc blau (Callinectes sapidus) és un crustaci decàpode que presenta cinc parells de potes; el seu cos està cobert d'un exoesquelet de color verd fosc.
En els mascles, les potes (pleòpodes) tenen un color gris-blavós, i és aquesta característica la que els ha donat el nom comú de cranc blau. No obstant això, en les femelles les puntes de les potes són de tonalitat vermellós-ataronjat.
Die Blaukrabbe oder Blaue Schwimmkrabbe (Callinectes sapidus) gehört zur Gattung Callinectes in der Familie der Schwimmkrabben (Portunidae). Sie ist im westlichen Atlantik heimisch, im 20. Jahrhundert aber in europäische Gewässer eingeschleppt worden. Die wissenschaftliche Bezeichnung setzt sich aus altgriechisch κάλλος kállos „schön“, νηκτής nēktḗs „Schwimmer“ und lat. sapidus „schmackhaft“ zusammen.
Der Carapax (Rückenpanzer) der Blaukrabbe wird zwischen 17,8 und 20 Zentimeter breit und etwa 7,5 bis 10,2 Zentimeter lang. Männchen werden größer als Weibchen[1]. Das Gewicht adulter Tiere liegt zwischen 0,45 und 0,90 Kilogramm. Der Rückenpanzer weist eine dunkelbraune, gräuliche, grünliche oder bläulich-grüne Färbung auf und besitzt auf jeder Seite orangefarbene Stacheln oder Dornen mit einer Breite von bis zu 8 Zentimetern. Die unteren Beine und das Abdomen sind weißlich gefärbt.
Die Scheren weisen je nach Geschlecht unterschiedliche Farbschattierungen auf. Die Scherenspitzen der Männchen sind bläulich und die der Weibchen rötlich gefärbt. Die Geschlechter können auch anhand der Bauchklappe oder Schürze unterschieden werden. Unter der Bauchklappe sind bei beiden Geschlechtern die Geschlechtsorgane verborgen. Beim Männchen ist die Klappe (Pleon) unter dem Bauch nicht zum Eiertragen geeignet und deshalb schmäler und hat die Form eines umgekehrten T.
Die Blaukrabbe besitzt wie alle Zehnfußkrebse fünf Beinpaare. Das vorderste Beinpaar wurde im Lauf der Evolution zu zwei kräftigen Scheren umgebildet. Die beiden Scheren sind unterschiedlich groß. Die größere Schere dient zum Aufbrechen von Beutetieren während mit der kleineren Schere die Nahrung zum Maul befördert wird. Das fünfte Beinpaar ist wie ein Paddel geformt und dient dem Schwimmen. Blaukrabben sind wie viele Zehnfußkrebse zur Autotomie fähig. Verlorene Gliedmaßen kann die Blaukrabbe regenerieren.
Die kurz gestielten Facettenaugen liegen direkt unter dem vorderen Rand des Carapax am Kopf. Zwischen den Augen befinden sich zwei kurze und dünne Fühler.
Ihren Trivialnamen verdankt diese Art der blauen Färbung der Beine, die auch weiße Flecken aufweisen können.
Eine Blaukrabbe wird rund zwei bis vier Jahre alt.
Die ursprüngliche Heimat der Blaukrabbe ist die Atlantikküste von Nordamerika und Südamerika von Nova Scotia bis Uruguay und im Golf von Mexiko. Heute ist sie als Neozoon in japanischen Gewässern, der Ostsee, Nordsee, dem Mittelmeer, der Adria und im Schwarzen Meer anzutreffen. Wahrscheinlich ist die Krabbe mit Ballastwasser eingeschleppt worden. In Europa wurde die Krabbe erstmals 1901 in Rochefort (Frankreich) beobachtet.[2]
Die Blaukrabbe lebt überwiegend in Mündungsgebieten von Flüssen und in flachen Küstengewässern bis in eine Tiefe von etwa 36 Metern, im Winter auch tiefer. Sie bevorzugt schlammige und sandige Böden.
Die Jungtiere benötigen eine Wassertemperatur von 15 bis 30 Grad Celsius. Die adulten Tiere können Wassertemperaturen von bis zu 10 Grad Celsius ertragen. Die Larven reagieren, im Gegensatz zu Jungtieren und adulten Tieren, empfindlich auf mittlere Salzkonzentrationen im Wasser, die unter 20 PSU liegen.
Nach der Paarung kehren die Weibchen in die flachen salzigen Küstengewässer zurück, während die Männchen sich in Flussmündungen aufhalten.
Sie gräbt sich im Schlamm ein oder versteckt sich in Seegräsern, um so ihrer Beute aufzulauern oder sich vor Feinden zu schützen. Die Blaukrabbe ist gegenüber anderen Arten ziemlich aggressiv.
Sie zählt nicht zu den bedrohten Tierarten, aber wasserverunreinigende Stoffe von Bauernhöfen, Kläranlagen und Chemikalien können schwerwiegende Folgen für die Blaukrabbe haben, da diese Schadstoffe einen niedrigen Sauerstoffgehalt verursachen, unter dem sie sehr zu leiden hat.
Die Blaukrabbe konkurriert mit anderen Krebstieren (Crustacea) bei der Nahrungssuche und -aufnahme. Sie ist ein Allesfresser. Ihr Nahrungsspektrum umfasst dünnschalige Muscheln (Bivalvia) wie z. B. Miesmuscheln (Mytilidae), junge Krebstiere, Fische, Würmer sowie Pflanzen. Sie scheut aber auch nicht vor verwesendem Aas zurück. Bei Nahrungsknappheit neigt sie zu Kannibalismus.
Zu den natürlichen Feinden zählen der Rote Umberfisch (Sciaenops ocellatus), der Atlantische Umberfisch (Micropogonias undulatus), die Amerikanische Silbermöwe (Larus argentatus smithsonianus), verschiedene Reiher-Arten (Ardeidae) sowie Meeresschildkröten (Cheloniidae).
Der Mensch hat die Blaukrabbe als Delikatesse für sich entdeckt. Unter anderem wird sie in Griechenland kommerziell gefischt.[2] Der jährliche Fang liegt zwischen 3,16 und 5,3 Millionen Kilogramm im Wert von 1.928.000 bis 4.474.000 US$.
Wichtiger Parasit der Blaukrabbe ist Hematodinium perezi, ein Dinoflagellat[3]. Auch die zu den Microsporidia gehörende Ameson michaelis und die Amöbe Paramoeba perniciosa können zu hoher Mortalität führen[4]. Der im Nervengewebe parasitierende Saugwurm Microphallus basodactylophallus und andere Microphallus-Arten, für die die Blaukrabbe Zwischenwirt ist[5] verursachen normalerweise nur geringe Schäden. Ist der Saugwurm von dem Hyperparasiten Urosporidium crescens befallen, kann dies nach dem Fang der Krabbe zu unappetitlichen schwarzen Verfärbungen führen, die ihren Handelswert mindern.[6]
Der die Kiemen besiedelnde Ciliat Lagenophrys callinectes schädigt die Blaukrabbe bei geringen Dichten kaum, kann aber bei Massenauftreten zum Ersticken führen.
Die Blaukrabbe wird mit 12 bis 18 Monaten geschlechtsreif. Die Weibchen paaren sich nur einmal, unmittelbar nach der letzten Häutung, während die Männchen sich öfter paaren. Wie alle Schalentiere muss sich auch die Blaukrabbe in regelmäßigen Abständen häuten weil ihre Schale nicht mitwächst.
Nach der Häutung ist die Schale des Weibchens für kurze Zeit weich. Diese Zeit nutzt das Männchen um sich mit dem Weibchen zu paaren. Das Weibchen verfügt über die Fähigkeit das Sperma des Männchens über längere Zeit unter ihrer Schale zu lagern.
Das Weibchen laicht etwa nach zwei bis neun Monaten nach der Paarung. Der Laich besteht aus bis zu zwei Millionen Eiern. Die Laichzeit beginnt im Dezember und endet im Oktober, wobei der Höhepunkt im Frühling und Sommer ist. Nachdem das Weibchen abgelaicht hat werden die Eier mit dem gelagerten Sperma befruchtet und auf die winzigen Haaranhängsel, die sich auf ihren Bauch befinden, gelegt.
Die Inkubationszeit beträgt etwa 14 Tage. Innerhalb von zwei Monaten durchlaufen die Larven acht Stadien, bevor sie beginnen wie Krabben auszusehen.
Tiere aus dem südlichen Teil des Verbreitungsgebiets, von Florida an südwärts, wurden nach brasilianischen Tieren von der Erstbeschreiberin der Art, der Meeresbiologin Mary J. Rathbun als Unterart Callinectes sapidus acutidens beschrieben. Da beide Formen durch Übergänge miteinander verbunden sind und teilweise im selben Habitat nebeneinander leben, wird die Unterart heute in der Regel nicht mehr anerkannt.[7][8]
Blaukrabben gehören im gesamten Bereich der US-amerikanischen Ostküste, aber insbesondere im Bereich der Chesapeake Bay, spätestens seit dem Beginn der europäischen Besiedlung dieser Region zu den wichtigen Arten für die kommerzielle Fischerei.[9]
Die Blaukrabbe oder Blaue Schwimmkrabbe (Callinectes sapidus) gehört zur Gattung Callinectes in der Familie der Schwimmkrabben (Portunidae). Sie ist im westlichen Atlantik heimisch, im 20. Jahrhundert aber in europäische Gewässer eingeschleppt worden. Die wissenschaftliche Bezeichnung setzt sich aus altgriechisch κάλλος kállos „schön“, νηκτής nēktḗs „Schwimmer“ und lat. sapidus „schmackhaft“ zusammen.
Gaforrja blu është një lloj gaforreje që jeton në Atlantikun Perëndimor, kryesisht në brigjet lindore të SHBA-ve dhe në Gjirin e Meksikës.
Mund të arrijë gjerësi deri në 23 cm, dhe ka ngjyrë të theksuar bojëqielli, e me pinca e kthetra ngjyrë të kuqe. Është lloj i huaj pushtues në Detin Mesdhe, dhe në 10 vitet e fundit ka pushtuar dhe bregdetin shqiptar, sidomos zonat lagunore. Shtimi i tepërt i saj ka dëmtuar llojet vendase të gaforreve. Në Lagunën e Vilunit, gaforrja blu tashmë është gaforrja dominuese, duke zhdukur apo zvogëluar tej mase popullatat e gaforreve vendase.
நீலக்கால் நண்டு (Callinectes sapidus or Chesapeake or Atlantic blue crab) என்பது கிரஸ்தேசியன் குடும்பத்தைச் சேர்ந்த உயிரினமாகும்.இவ்வகை நண்டு மேற்கு அட்லாண்டிக் கடல் பகுதியிலும் மத்திய அமெரிக்காவின் பசிபிக் கடற்கரைப் பகுதிகளிலும் மெக்சிகோ வளைகுடாப்பகுதிகளிலும் காணப்படுகிறது. உலகில் பல இடங்களில் பிடிபடும், அதிலும் பாக்கு நீரிணைப் பகுதியில் இந்த வகை நீலக்கால் நண்டுகளை அதிகளவில் காணலாம், தென் இந்திய மீனவர்களும், இலங்கை மீனவர்களும் இந்த பகுதியில் நீலக்கால் நண்டுகளைப் பிடிக்கின்றனர். இந்த வகை நீலக்கால் நண்டுகள் மேற்கத்திய நாடுகளுக்குப் பெருமளவில் ஏற்றுமதியும் செய்யப்படுகின்றன.
இந்த வகை நீலக்கால் நண்டை இலங்கை மீனவர்கள் நாச்சிகுடா நண்டு என்று சொல்வார்கள், நாச்சிக்குட என்பது பாக்கு நீரிணையில் மன்னார் தொடக்கம் பூநகரிவரை இலங்கை பக்கமாக இருக்கும் ஒரு குடாவாகும். அதேவேளை தமிழ்நாட்டின் கோடியாகரை போன்ற இடங்களிலும் இந்த நண்டு அதிகமாக பிடிக்கப்படுகின்றன. இந்த பிரதேசத்தில் இந்தவகை நண்டு மாரி காலங்களில் பெருமளவாக பிடிபடும். இரண்டு நண்டுகள் ஒரு கி.கிராம் அளவுக்கு இதன் நிறை இருக்கும், மற்ற வகை நண்டுகளை விட இந்த நண்டு சுவையாகவும், நண்டு குழம்பின் வாசனையும், நண்டு தசைகளும் அதிகமாக இருக்கும். ஆனால் இலங்கையை பொறுத்தவகையில் இந்த நண்டு விலை கொஞ்சம் அதிகம்தான், அதேவேளை அனைத்து காலங்களிலும் இந்த நண்டு கிடைப்பதும் அரிது என்றுதான் சொல்லலாம்.
நீலக்கால் நண்டு (Callinectes sapidus or Chesapeake or Atlantic blue crab) என்பது கிரஸ்தேசியன் குடும்பத்தைச் சேர்ந்த உயிரினமாகும்.இவ்வகை நண்டு மேற்கு அட்லாண்டிக் கடல் பகுதியிலும் மத்திய அமெரிக்காவின் பசிபிக் கடற்கரைப் பகுதிகளிலும் மெக்சிகோ வளைகுடாப்பகுதிகளிலும் காணப்படுகிறது. உலகில் பல இடங்களில் பிடிபடும், அதிலும் பாக்கு நீரிணைப் பகுதியில் இந்த வகை நீலக்கால் நண்டுகளை அதிகளவில் காணலாம், தென் இந்திய மீனவர்களும், இலங்கை மீனவர்களும் இந்த பகுதியில் நீலக்கால் நண்டுகளைப் பிடிக்கின்றனர். இந்த வகை நீலக்கால் நண்டுகள் மேற்கத்திய நாடுகளுக்குப் பெருமளவில் ஏற்றுமதியும் செய்யப்படுகின்றன.
Callinectes sapidus (from the Ancient Greek κάλλος,"beautiful" + nectes, "swimmer", and Latin sapidus, "savory"), the blue crab, Atlantic blue crab, or regionally as the Chesapeake blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.
C. sapidus is of considerable culinary and economic importance in the United States, particularly in Louisiana, the Carolinas, the Chesapeake Bay, Delaware, and New Jersey. It is the Maryland state crustacean and the state's largest commercial fishery.[2] Due to overfishing and environmental pressures some of the fisheries have seen declining yields, especially in the Chesapeake Bay fishery.
Unlike other fisheries affected by climate change, blue crab is expected to do well; warming causes better breeding conditions, more survivable winters, and a greater range of habitable areas in the Atlantic coast.[3][4] Whether this will have negative effects on the surrounding ecosystems from an increased crab population is still unclear.[3]
C. sapidus is a decapod crab of the swimming crab family Portunidae. The genus Callinectes is distinguished from other portunid crabs by the lack of an internal cartilaginous spine on the carpus (the middle segment of the claw), as well as by the T-shape of the male abdomen.[6] Blue crabs may grow to a carapace width of 23 cm (9 in). C. sapidus individuals exhibit sexual dimorphism. Males and females are easily distinguished by the shape of the abdomen (known as the "apron") and by color differences in the chelipeds, or claws. The abdomen is long and slender in males, but wide and rounded in mature females. A popular mnemonic is that the male's apron is shaped like the Washington Monument, while the mature female's resembles the dome of the United States Capitol.[5] Claw color differences are more subtle than apron shape. The immovable, fixed finger of the claws in males is blue with red tips, while females have orange coloration with purple tips.[7] A female's abdomen changes as it matures: an immature female has a triangular-shaped abdomen, whereas a mature female's is rounded.[8]
Other species of Callinectes may be easily confused with C. sapidus because of overlapping ranges and similar morphology. One species is the lesser blue crab (C. similis). It is found further offshore than the common blue crab, and has a smoother granulated carapace. Males of the lesser blue crab also have mottled white coloration on the swimming legs, and females have areas of violet coloration on the internal surfaces of the claws.[9] C. sapidus can be distinguished from another related species found within its range, C. ornatus, by number of frontal teeth on the carapace. C. sapidus has four, while C. ornatus has six.[10]
The crab's blue hue stems from a number of pigments in the shell, including alpha-crustacyanin, which interacts with a red pigment, astaxanthin, to form a greenish-blue coloration. When the crab is cooked, the alpha-crustacyanin breaks down, leaving only the astaxanthin, which turns the crab to a bright orange-red color.[11]
Organochlorides are found by Sheridan et al 1975 to be transferred to the C. sapidus hepatopancreas.[12]: 7 [13] They find that among organochlorides, DDT specifically is converted both to DDE and DDD in this crab.[14]: 491
C. sapidus is native to the western edge of the Atlantic Ocean from Cape Cod to Argentina and around the entire coast of the Gulf of Mexico.[15][16] It has recently been reported north of Cape Cod in the Gulf of Maine, potentially representing a range expansion due to climate change.[17] It has been introduced (via ballast water) to Japanese and European waters, and has been observed in the Baltic, North, Mediterranean, and Black Seas.[18] The first record from European waters was made in 1901 at Rochefort, France.[19] In some parts of its introduced range, C. sapidus has become the subject of crab fishery, including in Greece, where the local population may be decreasing as a result of overfishing.[19]
The natural predators of C. sapidus include eels, drum, striped bass, spot, trout, some sharks, humans, cownose rays, and whiptail stingrays. C. sapidus is an omnivore, eating both plants and animals. It typically consumes thin-shelled bivalves, annelids, small fish, plants, and nearly any other item it can find, including carrion, other C. sapidus individuals, and animal waste.[20] In salt marshes, C. sapidus will eat marsh periwinkles, Littoraria irrorata during high tides.[21][22] Although an aquatic predator, C. sapidus will remain in shallow pits in salt marshes at low tide and ambush intertidal prey such as fiddler crabs (e.g., Minuca pugnax) and purple marsh crabs (Sesarma reticulatum) [23] C. sapidus may be able to control populations of the invasive green crab, Carcinus maenas; numbers of the two species are negatively correlated, and C. maenas is not found in the Chesapeake Bay, where C. sapidus is most abundant.[24]
C. sapidus is subject to a number of diseases and parasites.[25] These include a number of viruses, bacteria, microsporidians, ciliates, and others.[25] The nemertean worm Carcinonemertes carcinophila commonly parasitizes C. sapidus, especially females and older crabs, although it has little adverse effect on the crab.[25] A trematode that parasitizes C. sapidus is itself targeted by the hyperparasite Urosporidium crescens.[25] The most harmful parasites may be the microsporidian Ameson michaelis, the amoeba Paramoeba perniciosa and the dinoflagellate Hematodinium perezi, which causes "bitter crab disease".[26]
In 2021, scientists from the University of Maryland completed DNA sequencing on C. sapidus's genome in Baltimore after six years of research to help better understand the species.[27] This genetic map is expected to help scientists understand how the blue crabs will be affected by climate change and warmer water temperatures, along with which mutations cause disease, traits that influence meat production, and which females have the best reproductive ability.[28]
Eggs of C. sapidus hatch in high-salinity waters of inlets, coastal waters, and mouths of rivers, and are carried to the ocean by ebb tides.[7] During seven planktonic (zoeal) stages, blue crab larvae float near the surface and feed on microorganisms they encounter. After the eighth zoeal stage, larvae molt into megalopae. This larval form has small claws called chelipeds for grasping prey items.[29] Megalopae selectively migrate upward in the water column as tides travel landward toward estuaries. Eventually, blue crabs arrive in brackish water, where they spend the majority of their lives. Chemical cues in estuarine water prompt metamorphosis to the juvenile phase, after which blue crabs appear similar to the adult form.[7]
A blue crab grows by shedding its exoskeleton, or molting, to expose a new, larger exoskeleton. After it hardens, the new shell fills with body tissue. Shell hardening occurs most quickly in low-salinity water where high osmotic pressure allows the shell to become rigid soon after molting.[29] Molting reflects only incremental growth, making age estimation difficult.[7] For blue crabs, the number of molts in a lifetime is fixed at about 25. Females typically exhibit 18 molts after the larval stages, while postlarval males molt about 20 times.[30] Male blue crabs tend to grow broader and have more accentuated lateral spines than females.[29] Growth and molting are profoundly influenced by temperature and food availability. Higher temperatures and greater food resources decrease the period of time between molts, as well as the change in size during molts (molt increment). Salinity and disease also have subtle impacts on molting and growth rate.[6] Molting occurs more rapidly in low-salinity environments. The high osmotic pressure gradient causes water to quickly diffuse into a soft, recently molted blue crab's shell, allowing it to harden more quickly. The effects of diseases and parasites on growth and molting are less well understood, but in many cases have been observed to reduce growth between molts. For example, mature female blue crabs infected with the parasitic rhizocephalan barnacle Loxothylacus texanus appear extremely stunted in growth when compared to uninfected mature females.[29] Blue crabs may reach maturity within one year of hatching in the Gulf of Mexico, while Chesapeake Bay crabs may take up to 18 months to mature.[30] As a result of different growth rates, commercial and recreational crabbing occur year-round in the Gulf of Mexico, while crabbing seasons are closed for colder parts of the year in northern states.
Mating and spawning are distinct events in blue crab reproduction. Males may mate several times and undergo no major changes in morphology during the process. Female blue crabs mate only once in their lifetimes during their pubertal, or terminal, molt. During this transition, the abdomen changes from a triangular to a semicircular shape. Mating in blue crab is a complex process that requires precise timing of mating at the time of the female's terminal molt. It generally occurs during the warmest months of the year. Prepubertal females migrate to the upper reaches of estuaries, where males typically reside as adults. To ensure that a male can mate, he actively seeks a receptive female and guards her for up to seven days until she molts, when insemination occurs. Crabs compete with other individuals before, during, and after insemination, so mate guarding is very important for reproductive success. After mating, a male must continue to guard the female until her shell has hardened.[29] Inseminated females retain spermatophores for up to one year, which they use for multiple spawnings in high salinity water.[31] During spawning, a female extrudes fertilized eggs onto her swimmerets and carries them in a large egg mass, or sponge, while they develop. Females migrate to the mouth of the estuary to release the larvae, the timing of which is believed to be influenced by light, tide, and lunar cycles. Blue crabs have high fecundity; females may produce up to 2 million eggs per brood.[29]
Migration and reproduction patterns differ between crab populations along the East Coast and the Gulf of Mexico. A distinct and large-scale migration occurs in Chesapeake Bay, where C. sapidus undergoes a seasonal migration of up to several hundred miles. In the middle and upper parts of the bay, mating peaks in mid- to late summer, while in the lower bay , peaks in mating activity occur during spring and late summer through early fall. Changes in salinity and temperature may impact time of mating because both factors are important during the molting process.[29] After mating, the female crab travels to the southern portion of the Chesapeake, using ebb tides to migrate from areas of low salinity to areas of high salinity,[32] fertilizing her eggs with sperm stored during her single mating months or almost a year before.[33]
Spawning events in the Gulf of Mexico are less pronounced than in estuaries along the East Coast, like the Chesapeake. In northern waters of the Gulf of Mexico, spawning occurs in the spring, summer, and fall, and females generally spawn twice. During spawning, females migrate to high -salinity waters to develop a sponge, and return inland after hatching their larvae. They develop their second sponge inland, and again migrate to the high-salinity waters to hatch the second sponge. After this, they typically do not re-enter the estuary. Blue crabs along the southernmost coast of Texas may spawn year-round.[30]
Commercial fisheries for C. sapidus exist along much of the Atlantic coast of the United States, and in the Gulf of Mexico. Although the fishery has been historically centered on the Chesapeake Bay, contributions from other localities are increasing in importance.[34] In the past two decades, most commercial crabs have been landed in four states: Maryland, Virginia, North Carolina, and Louisiana. Weight and value of harvests since 2000 are listed below.[35]
As early as the 1600s, the blue crab was an important food item for Native Americans and European settlers in the Chesapeake Bay area. Soft and hard blue crabs were not as valuable as fish, but gained regional popularity by the 1700s. Throughout their range, crabs were also an effective bait type for hook-and-line fisheries. Rapid perishing limited the distribution and hindered the growth of the fishery. Advances in refrigeration techniques in the late 1800s and early 1900s increased demand for blue crab nationwide.[29]
The early blue crab fishery along the Atlantic Coast was casual and productive because blue crabs were extremely abundant. In the lower Chesapeake Bay, crabs were even considered a nuisance species because they frequently clogged the nets of seine fishermen. Early on, the blue crab fishery of the Atlantic states was well documented. Atlantic states were the first to regulate the fishery, particularly the Chesapeake states. For example, after observing a slight decline in harvest, the fishing commissions of Virginia and Maryland put size limits into place by 1912 and 1917, respectively. Catch-per-unit-effort at the time was determined by packing houses, or crab processing plants.[29]
The early history of the recreational blue crab fishery in the Gulf of Mexico is not well known.[30] Commercial crabbing was first reported in the Gulf of Mexico in the 1880s. Early crab fishermen used long-handled dip nets and drop nets among other simple fishing gear types to trap crabs at night. Blue crab spoiled quickly, which limited distribution and hindered the growth of the fishery for several decades.[36] The first commercial processing plant in Louisiana opened in Morgan City in 1924. Other plants opened soon after, although commercial processing of hard blue crabs was not widespread until World War II.[30]
Louisiana now has the world's largest blue-crab fishery. Commercial harvests in the state account for over half of all landings in the Gulf of Mexico.[30] The industry was not commercialized for interstate commerce until the 1990s, when supply markedly decreased in Maryland due to problems (see above) in Chesapeake Bay. Since then, Louisiana has steadily increased its harvest. In 2002, Louisiana harvested 22% of the nation's blue crab. That number rose to 26% by 2009 and 28% by 2012. The vast majority of Louisiana crabs are shipped to Maryland, where they are sold as "Chesapeake" or "Maryland" crab. Louisiana's harvest remained high in 2013, with 17,597 metric tons of blue crab valued at $51 million.[35] In addition to commercial harvesting, recreational crabbing is very popular along Louisiana's coast.[30]
The Chesapeake Bay has had the largest blue crab harvest for more than a century. Maryland and Virginia are usually the top two Atlantic coast states in annual landings, followed by North Carolina.[35] In 2013, crab landings were valued at $18.7 million from Maryland waters and $16.1 million from Virginia waters.[37] Although crab populations are currently declining, blue crab fishing in Maryland and Virginia remains a livelihood for thousands of coastal residents. As of 2001, Maryland and Virginia collectively had 4,816 commercial crab license holders.[38] Three separate licenses are required for each of the three major jurisdictional areas: Maryland, the Potomac River, and Virginia waters.[39] While the Bay’s commercial sector lands the majority of hard crab landings and nearly all peeler or soft crab landings, the recreational fishery is also significant.[39] In 2013, an estimated 1.8 million kilograms (3.9 million pounds) of blue crab were harvested recreationally.[37]
Blue crab populations naturally fluctuate with annual changes in environmental conditions. They have been described as having a long-term dynamic equilibrium, which was first noted after irregular landings data in the Chesapeake in 1950.[40] This tendency may have made it difficult for managers to predict the severe decline of the Chesapeake’s blue crab populations. Once considered an overwhelmingly abundant annoyance, the declining blue crab population is now the subject of anxiety among fishermen and managers. Over the decade between the mid-1990s to 2004, the population fell from 900 million to around 300 million, and harvest weight fell from 52,000 to 28,000 tonnes (57,000 to 31,000 short tons). Revenue fell further, from $72 million to $61 million. Long-term estimates say that the overall Chesapeake population decreased around 70% in the last few decades. Even more alarming, the number of females capable of reproducing, known as spawning age females, has plummeted 84% in just a few decades. Survival and addition of juveniles to the harvestable crab population is also low.[41] Many factors are to blame for low blue crab numbers, including high fishing pressure, environmental degradation, and disease prevalence.[42] The 2018 reduction in H-2B visas available for seasonal workers is affecting Maryland's 20 crab processors, which typically employ about 500 foreign workers, but the effect this will have on the crab fishery is not yet clear.[43]
Many types of gear have been used to catch blue crabs along the Atlantic and Gulf Coasts.[29] Initially, people used very simple techniques and gear, which included hand lines, dip nets, and push nets among a variety of other gear types. The trotline, a long baited twine set in waters 5–15 feet deep, was the first major gear type used commercially to target hard crabs.[6] Use of commercial trotlines is now mostly limited to the tributaries of the Chesapeake Bay. In the Gulf of Mexico, trotline use drastically declined after invention of the crab pot in 1938. Crab pots are rigid, box-like traps made of hexagonal or square wire mesh. They possess between two and four funnels that extend into the trap, with the smaller end of the funnel inside of the trap. A central compartment made of smaller wire mesh holds bait. Crabs attracted by odorant plumes from the bait, often an oily fish, enter the trap through the funnels and cannot escape.[29]
Species other than blue crab are often caught incidentally in crab pots, including fish, turtles, conch, and other crab species. In Georgia, hermit crabs (Pagurus spp.), channeled whelk (Busycon canaliculatum), spider crabs (Libinia spp.), and stone crabs (Menippe mercenaria) were the most common species observed as bycatch in commercial crab pots.[44] Of important concern is the diamondback terrapin, Malaclemys terrapin. The blue crab and diamondback terrapin have overlapping ranges along the East and Gulf Coasts of the United States. Because the funnels in a crab pot are flexible, small terrapins may easily enter and become entrapped. Traps are checked every 24 hours or less, frequently resulting in drowning and death of terrapins. Crab pot bycatch may reduce local terrapin populations to less than half. To reduce terrapin entrapment, bycatch reduction devices (BRDs) may be installed on each of the funnels in a crab pot.[45] BRDs effectively reduce bycatch (and subsequently mortality) of small terrapins without affecting blue crab catch.[46]
Because of its commercial and environmental value, C. sapidus is the subject of management plans over much of its range.[16][47] In 2012, the C. sapidus population in Louisiana was recognized as a certified sustainable fishery by the Marine Stewardship Council.[48] It was the first and remains the only certified sustainable blue crab fishery worldwide.[49] For the state to maintain its certification, it must undergo annual monitoring and conduct a full re-evaluation five years after the certification date.[50]
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{{cite journal}}: Cite journal requires |journal= (help) {{cite journal}}: Cite journal requires |journal= (help) {{cite journal}}: Cite journal requires |journal= (help) {{cite journal}}: Cite journal requires |journal= (help) Blue crab escaping from the net along the Core Banks of North Carolina. Callinectes sapidus (from the Ancient Greek κάλλος,"beautiful" + nectes, "swimmer", and Latin sapidus, "savory"), the blue crab, Atlantic blue crab, or regionally as the Chesapeake blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.
C. sapidus is of considerable culinary and economic importance in the United States, particularly in Louisiana, the Carolinas, the Chesapeake Bay, Delaware, and New Jersey. It is the Maryland state crustacean and the state's largest commercial fishery. Due to overfishing and environmental pressures some of the fisheries have seen declining yields, especially in the Chesapeake Bay fishery.
Unlike other fisheries affected by climate change, blue crab is expected to do well; warming causes better breeding conditions, more survivable winters, and a greater range of habitable areas in the Atlantic coast. Whether this will have negative effects on the surrounding ecosystems from an increased crab population is still unclear.
La jaiba (Callinectes sapidus) es un crustáceo decápodo nativo de la costa occidental del océano Atlántico. Su cuerpo está cubierto de un exoesqueleto color verde oscuro.
Son especímenes activos y voraces. Su dieta está basada en crustáceos, peces, gran variedad de moluscos y algas; aceptan sin problemas carroña.
Como el resto de los crustáceos, son ovíparos. Se reproducen en aguas próximas a las costas, en primavera y verano. Se calcula que la fecundidad de una hembra de tamaño promedio es de 700 000 a 2 000 000 de huevos.
La jaiba azul es nativa de la costa occidental del Océano Atlántico, desde Nueva Escocia hasta Argentina, y alrededor de toda la costa del Golfo de México.[1][2] También se ha introducido en aguas japonesas y europeas, y se ha observado en los mares Báltico, del Norte, Mediterráneo y Negro.[3] El primer registro de su presencia en las aguas europeas se llevó a cabo en 1901 en Rochefort, Francia.[4] En algunas partes de su área de distribución introducido, C. sapidus se ha convertido en el objetivo de pesca de cangrejos, incluso en Grecia, donde la población local puede estar disminuyendo como consecuencia de la sobrepesca.[4] Son muy comunes en Sudamérica, en especial en las costas del Océano Pacífico.
Habitan en costas tropicales y templadas, en aguas de bahías, lagunas costeras, esteros y desembocaduras de los ríos, a una temperatura entre los 18 y los 23 °C, y en las playas a profundidades de entre 40 cm y 2 m. Pueden vivir entre 3 y 8 años. También pueden habitar en costas con agua fría a temperatura inferior a los 18 °C y con oleaje moderado. Viven entre rocas y algas flotantes y rara vez salen fuera del agua.
El caparazón de Callinectes sapidus puede crecer hasta un ancho de 23 cm. Se puede distinguir de otras especies relacionadas que habitan en la misma área por el número de dientes frontales en su caparazón; C. sapidus tiene cuatro, mientras que C. ornatus tiene seis.[5]
Los machos y las hembras de C. sapidus se pueden distinguir por el dimorfismo sexual en la forma del abdomen (conocido como el «delantal»): es largo y delgado (estrecho) en los machos, pero ancho y redondeado en las hembras maduras. Los cambios del abdomen de las hembras se ven a medida que estas maduran: en las hembras inmaduras, el abdomen tiene forma triangular, mientras que en las maduras es redondo.[6]
La tonalidad azul se deriva de una serie de pigmentos en el caparazón, incluyendo la alfa-crustacianina, que interactúa con un pigmento rojo, la astaxantina, para formar una coloración azul verdosa. Cuando se cocina el cangrejo, la alfa-crustacianina se destruye, dejando sólo la astaxantina, que cambia su color a un rojo anaranjado o un rosa fuerte.[7]
Los depredadores naturales de C. sapidus incluyen anguilas, rayas, truchas, algunos tiburones rastreros, rayas nariz de vaca y los seres humanos. La jaiba azul es omnívora, ya que come plantas y animales. Normalmente consume bivalvos de concha fina, anélidos, pequeños peces, plantas, y casi cualquier otro elemento que pueda encontrar, incluyendo carroña, otros individuos de C. sapidus y residuos animales.[8] Es capaz de controlar las poblaciones de cangrejo verde invasoras, Carcinus maenas. Los números de las dos especies se correlacionan negativamente, y C. maenas no se encuentra en la bahía de Chesapeake, donde C. sapidus es más frecuente.[9]
La jaiba azul es propensa a una serie de enfermedades y parásitos.[10] Se incluyen una serie de virus, bacterias, microsporidios, ciliados y otros.[10] Carcinonemertes carcinophila comúnmente parásita a C. sapidus, especialmente a las hembras y los cangrejos viejos, aunque no tiene gran peligrosidad en la salud del cangrejo.[10] El hiperparásito Urosporidium crescens también suele parasitar a este cangrejo.[10] Los parásitos más dañinos son Ameson michaelis, Paramoeba perniciosa y Hematodinium perezi, que le provocan la «enfermedad del cangrejo amargo».[11]
Las jaibas son apreciadas en la culinaria costera de casi todos los países de costa por su carne y por su relativa abundancia y fácil captura.
La jaiba (Callinectes sapidus) es un crustáceo decápodo nativo de la costa occidental del océano Atlántico. Su cuerpo está cubierto de un exoesqueleto color verde oscuro.
Sinitaskurapu (Callinectes sapidus) on Atlantin valtameren länsireunalta kotoisin oleva taskurapulaji, joka kuuluu sinitaskurapujen Portunidae-heimoon. Se on kaupallisesti merkittävä erityisesti Yhdysvalloissa.[2][3]
Kun mukaan lasketaan sivupiikit, sinitaskuravun selkäkilpi on pituuttaan yli kaksi kertaa leveämpi.[2] Täysikasvuisen yksilön selkäkilpi on keskimäärin 18 senttimetriä leveä ja 9–10 senttimetriä pitkä ja painaa 450–900 grammaa; naaras on hieman koirasta pienempi. Rapu on selkäpuolelta harmaanvihreä, sinivihreä tai ruskeanvihreä ja vatsapuolelta ja raajojen tyvestä valkoinen.[2][3] Selkäkilvessä ja raajoissa on tavallisesti myös muita värisävyjä.[2] Kilven eturaunassa on keskiviivan molemmin puolin 11 sakaraa, joista 2 keskimmäistä ovat leveät ja tylppä- tai teräväkärkiset ja 9 laitimmaista kapeammat ja teräväkärkiset. Aivan reunimmainen sakara on kehittynyt suureksi piikiksi, joka osoittaa suoraan sivulle. Pyrstön päättökilpi on suikea ja leveyttään pitempi.[2] Ravulla on tappisilmät, joilla se pystyy näkemään lähes kaikkiin suuntiin samalla kertaa.[3]
Muiden kymmenjalkaisten tapaan sinitaskuravulla on viisi raajaparia, joista etummaiset ovat kehittyneet voimakkaiksi saksiksi ja neljä takimmaista kävelyraajoiksi.[2][3] Sakset ovat koirailla siniset ja sukukypsillä naarailla oranssit, ja niiden terissä on epätasainen hammaslaita ja varressa kolme piikkiä. Takimmaisten raajojen päät ovat kehittyneet uimiseen soveltuviksi litteiksi levyiksi.[2] Rapu pystyy kasvattamaan itselleen uuden raajan menettämänsä tilalle kahden kuorenvaihdon kautta.[3]
Sinitaskurapu on kotoisin Atlantin valtameren länsireunalta, jossa sen levinneisyysalue ulottuu Nova Scotiasta pohjoisessa Pohjois-Argentiinaan etelässä ja käsittää myös Bermudan, Länsi-Intian saaret ja koko Karibianmeren. Se on levinnyt ihmisen mukana myös Pohjanmereen ja Ranskan lounaisrannikolle Koillis-Atlantille, Adrianmeren pohjoisosiin ja Italian etelärannikolle Välimeressä sekä Japanin lähivesiin.[2]
Sinitaskurapu elää matalikoilla ja estuaareissa liejuisessa tai hiekkaisessa pohjassa aina 90 metrin syvyyteen asti.[2] Yleensä se pysyttelee liejuun kaivautuneena tai merikasvien sekaan piiloutuneena väijymässä saalista.[3]
Sinitaskuravulla on usein loisia, joista ei tavallisesti ole sille juuri haittaa. Tavallisimpia ulkoloisia ovat erilaiset siimajalkaiset, madot ja juotikkaat ja sisäloisia siirat ja pienet madot. Sitä saalistavat aaltorummuttajat, haikarat, merikilpikonnat ja ihminen. Sen olemassaoloa uhkaavat myös merien hapenpuute ja saastuminen.[3]
Sinitaskurapu saavuttaa sukukypsyyden 12–18 kuukauden iässä. Sen kutuaika kestää joulukuusta lokakuuhun ja huipentuu kevään ja kesän aikana. Koiras kutee useita kertoja elämänsä aikana mutta naaras vain kerran. Parittelu tapahtuu pian naaraan viimeisen kuorenvaihdoksen jälkeen, minkä jälkeen koiras suojelee naarasta, kunnes tämän suojakuori on kovettunut.[3]
Naaras säilyttää koiraan sukusoluja kehossaan 2–9 kuukautta, minkä jälkeen se laskee kerralla jopa kaksi miljoonaa munaa ja hedelmöittää ne koiraan sukusoluilla. Hedelmöitämisen jälkeen naaras siirtää munat vatsassaan sijaitseviin pieniin karvoihin ja kantaa niitä kaksi viikkoa, kunnes niistä kuoriutuu toukkia.[3]
Toukista kehittyy aikuisia kahdeksan muodonvaihdoksen ja kahden kuukauden kuluttua. Ainoastaan yhdestä tai kahdesta naaraan laskemasta munasta kehittyy lopulta täysikasvuinen taskurapu, joka voi elää enimmillään kolmevuotiaaksi.[3]
Sinitaskurapu ei ole valikoiva ravinnon suhteen: se syö paitsi ostereita, simpukoita ja muita pohjaeläimiä myös kaloja ja kasveja sekä haaskoja ja muuta eloperäistä ainesta.[2]
Sinitaskurapu on kaupallisesti merkittävä erityisesti Yhdysvalloissa. 2000-luvulla sen vuotuinen kokonaissaalis oli 79 000–107 000 tonnia. Sitä myydään lähinnä tuoreena.[2]
Sinitaskurapu (Callinectes sapidus) on Atlantin valtameren länsireunalta kotoisin oleva taskurapulaji, joka kuuluu sinitaskurapujen Portunidae-heimoon. Se on kaupallisesti merkittävä erityisesti Yhdysvalloissa.
Callinectes sapidus
Callinectes sapidus (ou crabe bleu) est une espèce de crabes de la famille des Portunidae.
Cette espèce peuple l'ouest de l'océan Atlantique. Elle a été introduite dans l'est de l'Atlantique, dans le nord et l'est de la Méditerranée et au Japon.
En Méditerranée occidentale, il est signalé à partir de 1949 sur la lagune de Venise[1]. Concernant les lagunes méditerranéennes françaises, il a été observé en 1962 dans l’étang de Berre[2] et en 2014, puis pour la toute première fois en Corse dans la lagune de Biguglia[1],[3]. Cependant, après avoir échangé avec les pêcheurs des étangs d’Urbinu et de Palu[1], cette espèce avait déjà été observée avant cette date[3]. Il a de plus été observé en 2017 sur les côtes de l'Aude et des Pyrénées-Orientales en France et dans le delta de l'Èbre en Espagne, où l'espèce est considérée envahissante[4].
Ce crabe peut être confondu avec d'autres espèces de Callinectes comme C. bocourti, C. maracaiboensis, C. rathbunae, C. ornatus et C. danae.
Ce crabe de l'Atlantique peut atteindre une masse de 500 grammes.
Le crabe bleu fait l'objet d'une pêche artisanale sur la côte africaine atlantique, en particulier à la hauteur des pays de la zone équatoriale : Côte d'Ivoire, Ghana, Gabon, Cameroun. Il y prolifère facilement et il est une bonne ressource en protéines. Nous trouvons aujourd'hui cette espèce en Méditerranée notamment sur les côtes Adriatique de l'Albanie ainsi que dans le golfe de Gabes en Tunisie où sa pêche en est à ses prémices.
Volume de sa pêche : environ 106 000 tonnes par an. Aquaculture : elle est apparue depuis une dizaine d'années et produit 500 tonnes par an.
Le crabe bleu est parfois consommé comme crabe en mue.
Ce crabe figure sur une émission de Cuba de 1969 (valeur faciale : 4 c.).
Callinectes sapidus
Callinectes sapidus (ou crabe bleu) est une espèce de crabes de la famille des Portunidae.
Il granchio reale blu o granchio azzurro (Callinectes sapidus Rathbun, 1896) è un crostaceo decapode della famiglia dei Portunidi.[1] Specie autoctona delle coste atlantiche del continente americano, negli ultimi anni si sta diffondendo anche nel continente europeo.
La specie è originaria della sponda occidentale dell'oceano Atlantico, dove vive lungo le coste dell'intero continente americano, dalla Nuova Scozia all'Argentina[2], spingendosi anche lungo i corsi dei fiumi, poiché è in grado di tollerare salinità inferiori al tre per mille[3]. Tramite l'acqua incamerata per zavorrare le navi, la specie è stata accidentalmente introdotta in numerose altre parti del mondo (Mare del Nord, Mar Baltico, Mar Nero, Mediterraneo, Mar Giallo)[4]: in Italia è stata segnalata nel luglio 2008 in Basilicata[5], alla foce dei fiumi lungo la costa jonica, sulla costa adriatica dell'Abruzzo e della Puglia[6][7], e nell'alto adriatico da Goro ai lidi ferraresi[8]. Nell'agosto del 2019 sono stati pescati alcuni esemplari lungo la costa del Cilento, in località Ascea Marina di Velia (SA), e in località Sottomarina di Chioggia (VE). La specie si sta rapidamente diffondendo nelle Valli di Comacchio e nel ravennate, dove le acque calme e poco profonde si sono rivelate un habitat ideale per riproduzione e crescita. Dal novembre 2019 gli esemplari pescati in questa zona sono aumentati in maniera sensibile. Nell'agosto 2019 sono stati avvistati anche a Roca Vecchia Marina di Melendugno (LE), Lesina e Peschici (FG). Nel settembre 2019, sulla spiaggia di Marina di Pisciotta (SA), per la precisione sulla spiaggia Bandiera Blu denominata Acquabianca, sono stati avvistati altri esemplari. Nel 2020 sono stati avvistati anche nei pressi del golfo di Manfredonia, Vieste. A Vasto e San Salvo in Abruzzo, nei mari della Sardegna, prevalentemente nelle lagune della provincia di Oristano (Marceddì), sono stati pescati alcuni esemplari.
Altri esemplari sono stati catturati nel Golfo della Spezia precisamente nella costa Lericina di fronte a San Terenzo tra novembre 2021 e febbraio 2022 da pescatori locali.
La specie misura fino a 15 cm di lunghezza e 23 cm di larghezza: presenta corpo più largo che lungo, di forma ellittica, con due spuntoni ai due lati del corpo e margine anteriore seghettato. Le zampe sono piuttosto allungate, col primo paio tramutato in chele, più grandi nei maschi rispetto alle femmine: il colore del corpo è verde oliva superiormente, mentre il ventre è bianco-azzurrino e le zampe presentano l'attaccatura e la parte terminale di un colore blu intenso.
Durante il periodo della muta, sull'ultimo paio di zampe, appiattite ed adattate al nuoto, appaiono delle macchioline rosa, che acquistano via via colore divenendo sempre più rosse man mano che la muta si avvicina.
Si tratta di animali onnivori e piuttosto aggressivi: si nutrono di tutto ciò che riescono a catturare: bivalvi, anellidi, avannotti, carogne e piante.
Questi crostacei, nelle loro zone d'origine, vengono pescati in quantità per uso alimentare: in particolare, vengono considerati una prelibatezza quelli pescati nella baia di Chesapeake, dove essi costituiscono un'importante risorsa (valutata in oltre 100 milioni di dollari USA negli anni '90; attualmente la domanda è dimezzata)[9].
Per far fronte alla continua richiesta, gli Stati di Maryland e Virginia, che si affacciano sulla baia, hanno emanato speciali provvedimenti, volti a salvaguardare le popolazioni rimanenti, fra i quali il divieto di pescare esemplari di diametro inferiore ai 14 cm e restrizioni varie circa i periodi in cui effettuare la pesca.
A causa di tali provvedimenti, per far fronte alla forte domanda i due Stati americani hanno dovuto ricorrere all'importazione da altri Stati (Carolina del Nord, Louisiana, Florida e Texas)[10] od addirittura dal Sud-est Asiatico.
La pesca al granchio reale si effettua tramite particolari nasse, simili a quelle utilizzate per pescare le aragoste e denominate crab pot: tali nasse consistono in reticolati di filo metallico, posti attorno ad uno scheletro di legno o di metallo, a formare una gabbia di forma cubica con due entrate. Tali fori sono studiati in modo che l'animale, entrando attratto dall'esca (costituita da pezzetti di pesce o pollo fissati in una tasca di metallo per impedire agli animali di mangiarli), sia poi impossibilitato ad uscire dal foro. Le varie nasse vengono disposte in lunghi filari e controllate giornalmente, rimuovendo gli esemplari pescati ed eventualmente sostituendo le esche consumate.
I granchi vengono divisi in jimmies (maschi adulti), sallies (femmine immature) e sooks (femmine adulte): gli esemplari in fase di muta vengono separati dagli altri e piazzati in vasche di cemento di 90×150 cm a seconda della fase della muta in cui si trovano, per evitare atti di cannibalismo. Dopo la muta, si attendono circa due giorni per lasciar solidificare la nuova corazza dei granchi, dopodiché essi vengono congelati e venduti.
I pescatori amatoriali, per pescare occasionalmente qualche granchio, utilizzano sia i palangari, che le nasse: queste ultime, di dimensioni minori rispetto a quelle utilizzate commercialmente e dalle forme anche assai varie (oltre che cubiche, se ne trovano anche di forma piramidale o cilindrica). In queste trappole l'animale ha maggiori probabilità di fuga e perciò esse devono essere ispezionate più frequentemente, all'incirca ogni mezz'ora.
Un altro metodo assai semplice per pescare questi animali è quello di utilizzare una lampara per vederli nelle acque fluviali durante la notte e pescarli con un retino dalle maglie robuste, per evitare che questi animali danneggino la rete con le forti chele.
Negli Stati Uniti orientali, questi animali vengono bolliti in acqua, aceto e varie misture di erbe aromatiche: per poterli cuocere a piacimento, essi vengono gettati in scolapasta ed estratti una volta raggiunto il colore rosso, tipico dei crostacei bolliti.
Per estrarre la polpa del granchio, è necessario "scoperchiarlo" ed in seguito romperne le varie articolazioni, ricavando un quantitativo di carne modesto rispetto alle dimensioni totali dell'animale. Le branchie, solitamente rimosse, chiamate tomalley o mostarda (a causa del colore), vengono da alcuni considerate una delicatezza.
La carne del granchio blu, ricca di vitamina B12, viene utilizzata, oltre che come cibo istantaneo, anche come prezioso ingrediente del crab cake e di altre ricette locali. La carne può inoltre essere trattata per la conservazione, in appositi stabilimenti, ed essere venduta inscatolata.
I granchi catturati appena dopo la muta, e perciò muniti di guscio ancora molle, vengono privati delle interiora e delle branchie e fritti dopo essere stati immersi in una pastella di uova, farina ed erbe aromatiche.
Il granchio reale blu o granchio azzurro (Callinectes sapidus Rathbun, 1896) è un crostaceo decapode della famiglia dei Portunidi. Specie autoctona delle coste atlantiche del continente americano, negli ultimi anni si sta diffondendo anche nel continente europeo.
De blauwe zwemkrab (Callinectes sapidus) is een krab uit de familie Portunidae, ook wel zwemkrabben genoemd. Er is ook een krab met de naam blauwpootzwemkrab (Liocarcinus depurator), deze soort ziet er echter anders uit.
De blauwe zwemkrab dankt de naam aan de blauwe kleur poten, en is het makkelijkst te herkennen aan de zeer grote zijwaarts wijzende stekel aan iedere zijde van het schild. Het achterste paar poten is peddel-achtig afgeplat zoals bij alle zwemkrabben om beter te kunnen zwemmen. Mannetjes zijn van vrouwtjes te onderscheiden door de respectievelijk twee en vijf buikplaten, en volwassen vrouwtjes hebben twee rode scharen, mannetjes hebben blauwe scharen. De bovenzijde is olijfkleurig tot bruinzwart en de schildbreedte is maximaal 25 centimeter, mannetjes worden groter dan vrouwtjes.
Van oorsprong leeft deze soort in Amerika, maar al in de jaren dertig is de blauwe zwemkrab in Nederland aangetroffen en vermoed wordt dat de exoot zich verder zal verspreiden. De krab leeft langs de kust bij riviermondingen en kan in zowel zoet, brak als zout water overleven en ook de temperatuurstolerantie is groot; van enkele graden boven nul tot meer dan dertig graden. Deze soort staat bekend als delicatesse en het vlees wordt veel verhandeld. Het voedsel van de blauwe zwemkrab bestaat uit aas, zeedieren als zeesterren en ook wel andere krabben.
Deze soort plant zich in grote hoeveelheden voort; zo worden er twee keer eitjes afgezet en per keer zijn dat er gemiddeld meer dan een miljoen. De bijna volwassen vrouwtjes produceren een feromoon dat via de urine wordt uitgescheiden en de mannetjes lokt. Het eerste larvestadium is vrijzwemmend, later volgen nog zeven en soms acht andere stadia waarna de krab volwassen is. De larve kan namelijk alleen vervellen als het water rond de 20 graden is.
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De blauwe zwemkrab (Callinectes sapidus) is een krab uit de familie Portunidae, ook wel zwemkrabben genoemd. Er is ook een krab met de naam blauwpootzwemkrab (Liocarcinus depurator), deze soort ziet er echter anders uit.
Multimedia w Wikimedia Commons Kalinek błękitny (Callinectes sapidus) nazywany też krabem błękitnym lub niebieskim – gatunek kraba występujący w zachodniej części Oceanu Atlantyckiego i w Zatoce Meksykańskiej, zawleczony do Japonii i Europy.
Ma oliwkowo-zielono-białą skorupę, a jego nazwę zawdzięcza niebieskim odnóżom. Posiada głowotułów, odwłok, parę szczypiec, 3 pary odnóży krocznych oraz szczątki ostatniej pary odnóży, które uformowały się w "wiosła".
Szerokość skorupy jest zazwyczaj 2 razy większa, niż jej długość.
Porusza się bokiem. Dobrze pływa.
Szczypiec używa tylko w obronie własnej lub gdy ktoś chce mu zabrać pokarm.
Jest dominującym drapieżnikiem w ujściach rzek, lagunach i nabrzeżnych siedliskach zachodniego Atlantyku i Zatoki Meksykańskiej.
Gatunek o dużym znaczeniu użytkowym[2], jeden z najważniejszych gospodarczo gatunków krabów[3].
calli- znaczy piękny (stgr. κάλλος (kállos) – piękno, stgr. καλός (kalós) – piękny), nectes (stgr. νηκτης (nēktēs)) – pływak, a łac. sapidus – smaczny.
Kalinek błękitny (Callinectes sapidus) nazywany też krabem błękitnym lub niebieskim – gatunek kraba występujący w zachodniej części Oceanu Atlantyckiego i w Zatoce Meksykańskiej, zawleczony do Japonii i Europy.
Ubarwienie i wyglądMa oliwkowo-zielono-białą skorupę, a jego nazwę zawdzięcza niebieskim odnóżom. Posiada głowotułów, odwłok, parę szczypiec, 3 pary odnóży krocznych oraz szczątki ostatniej pary odnóży, które uformowały się w "wiosła".
RozmiarSzerokość skorupy jest zazwyczaj 2 razy większa, niż jej długość.
Sposób poruszania sięPorusza się bokiem. Dobrze pływa.
ZachowanieSzczypiec używa tylko w obronie własnej lub gdy ktoś chce mu zabrać pokarm.
WystępowanieJest dominującym drapieżnikiem w ujściach rzek, lagunach i nabrzeżnych siedliskach zachodniego Atlantyku i Zatoki Meksykańskiej.
Znaczenie gospodarczeGatunek o dużym znaczeniu użytkowym, jeden z najważniejszych gospodarczo gatunków krabów.
Nazwacalli- znaczy piękny (stgr. κάλλος (kállos) – piękno, stgr. καλός (kalós) – piękny), nectes (stgr. νηκτης (nēktēs)) – pływak, a łac. sapidus – smaczny.
Callinectes sapidus, conhecido pelos nomes comuns de siri-azul, siri-tinga ou simplesmente siri, é um pequeno crustáceo decápodo encontrado nas águas costeiras do Oceano Atlântico e Golfo do México. Em seu nome científico, calli é grego para "bonito", nectes para "nadador", e sapidus é latim para "saboroso". Dr. Mary Rathbun descreveu primeiramente o caranguejo-azul em 1896.
Os predadores naturais do siri-azul incluem enguias, trutas e alguns tubarões. O siri azul é omnívoro e consome tipicamente bivalves, anelídeos, peixes e quase todo o outro artigo que puderem encontrar, incluindo cadáveres.
A Baía de Chesapeake, que banha os estados de Maryland e Virginia, nos Estados Unidos, é famosa por seus siris-azuis, e eles são um dos artigos econômicos dos mais importantes colhidos dela. Em 1993 a colheita combinada do siri-azul alcançou o valor de 100 milhões de dólares US, mas este número desceu para 45 milhões no ano 2000.
É um dos maiores siris do litoral brasileiro, chegando a ter mais de 15 cm de envergadura. A fêmea é menor do que o macho. O último par de patas locomotoras é modificado, funcionando como remos. A quela pode pinçar com muita rapidez, causando pequenos ferimentos. A fêmea apresenta abdômen largo e arredondado, cujos apêndices são usados para carregar os ovos quando está ovígera.
O habitat preferido são as praias lodosas, tanto rasas como profundas, e pode subir pelos riachos que desembocam no mar, sendo abundante sua ocorrência em água salobra. Alimenta-se de detritos.
Ocorre em todo o litoral do Brasil.
A fêmea, na época da eclosão dos ovos, retorna ao mar para que as larvas se desenvolvam. Possui duas fases em seu ciclo de vida: uma marinha (fase pelágica) onde os ovos eclodem e os organismos se desenvolvem para o estádio de zoea, permanecendo em águas marinhas até o estádio de megalopa quando então migram para águas estuarinas em busca de proteção e salinidades mais baixas; e uma estuarina onde as megalopas recrutam (fase bentônica) e se desenvolvem para os primeiros estádios juvenis. Após sucessivas mudas, os animais se tornam adultos e aptos à cópula que ocorrerá em águas estuarina. A cópula é estimulada através de uma mudança na salinidade. Após a cópula, as fêmeas fertilizadas migram para regiões de maior salinidade. As fêmeas então liberam os ovos, resultantes da cópula em águas estuarinas de baixa salinidade, em águas marinhas de maior salinidade.
Está ameaçado pela pesca predatória, destruição do habitat e poluição.
O caranguejo-azul foi descoberto no estuário do rio Guadiana em junho de 2017.
Há registo de outros exemplares da mesma espécie capturados anteriormente no Estuário do Sado, o que indicia que a espécie estará numa fase de expansão na costa portuguesa, depois de provavelmente ter navegado, enquanto larva, na água de lastro de um navio que cruzou o Atlântico.[1]
Callinectes sapidus, conhecido pelos nomes comuns de siri-azul, siri-tinga ou simplesmente siri, é um pequeno crustáceo decápodo encontrado nas águas costeiras do Oceano Atlântico e Golfo do México. Em seu nome científico, calli é grego para "bonito", nectes para "nadador", e sapidus é latim para "saboroso". Dr. Mary Rathbun descreveu primeiramente o caranguejo-azul em 1896.
Mavi Yengeç (Callinectes sapidus) Bilimsel sınıflandırma Üst âlem: Eukaryota Âlem: Animalia Alt âlem: Metazoa Şube: Arthropoda Alt şube: Crustacea Sınıf: Malacostraca Alt sınıf: Eumalacostraca Üst takım: Eucarida Takım: Decapoda Alt takım: Pleocyemata İnfra takım: Brachyura Üst familya: Portunoidea Familya: PortunidaeMavi yengeç, bir yengeç türü.
Erkek yengeçlerin boyu 9 cm, genişliği, kabuğun iki yanındaki dikenlerle birlikte, 22 cm'dir. Dişiler ise bundan daha küçüktür. Boyları 7.5 cm, genişlikleri, yine aynı şartla, 18 cm'dir. Sırt kabuğunun iki yanında 9'ar adet diken bulunur.
Genellikle leşle beslenen mavi yengeçlerin saprotrof veya omnivor olanları da vardır. Yaşam döngülerinin farklı aşamalarında plankton, balık, bitki, yumuşakça ve kabuklularla beslenirler.
Kabuklular ile ilgili bu madde bir taslaktır. Madde içeriğini geliştirerek Vikipedi'ye katkıda bulunabilirsiniz. Mavi yengeç, bir yengeç türü.
Cua xanh Đại Tây Dương (danh pháp hai phần: Callinectes sapidus) hay còn gọi là ghẹ, là một loài giáp xác được tìm thấy trong vùng biển Đại Tây Dương phía tây Dương, bờ biển Thái Bình Dương của Trung Mỹ và Vịnh Mexico. Trên bờ biển Thái Bình Dương của Trung Mỹ, phần lớn là bỏ qua như là một nguồn thực phẩm do việc bắt loài cua này được coi là quá khó khăn. Đó là loài giáp xác của tiểu bang Maryland và được khai thác nhiều.[2]
Cua xanh Đại Tây Dương là loài bản địa ở rìa phía tây của Đại Tây Dương Nova Scotia đến Argentina và xung quanh toàn bộ bờ biển của vịnh Mexico.[3][4] Nó đã được du nhập (thông qua nước dằn tàu) đến vùng biển Nhật Bản và châu Âu, và đã được quan sát thấy ở biển Baltic, Biển Bắc, Địa Trung Hải và biển Đen.[5]
|month= bị phản đối (trợ giúp) Cua xanh Đại Tây Dương (danh pháp hai phần: Callinectes sapidus) hay còn gọi là ghẹ, là một loài giáp xác được tìm thấy trong vùng biển Đại Tây Dương phía tây Dương, bờ biển Thái Bình Dương của Trung Mỹ và Vịnh Mexico. Trên bờ biển Thái Bình Dương của Trung Mỹ, phần lớn là bỏ qua như là một nguồn thực phẩm do việc bắt loài cua này được coi là quá khó khăn. Đó là loài giáp xác của tiểu bang Maryland và được khai thác nhiều.
Callinectes sapidus Rathbun, 1896
Голубой краб[1][2][3][4] (лат. Callinectes sapidus) — ракообразное семейства Portunidae. Впервые описан Мэри Джейн Рэтбан.
Карапакс голубого краба достигает ширины 17,8—20 см и длины от 7,5—10,2 см. Самцы крупнее самок[5]. Вес половозрелых животных составляет от 0,45 до 0,90 кг. Спинной панцирь имеет тёмно-коричневую, сероватую, зеленоватую или голубовато-зелёную окраску и имеет на каждой стороне оранжевые шипы шириной до 8 см. Нижние конечности и брюшко имеют белёсую окраску.
Клешни имеют разные цветовые оттенки в зависимости от пола. Вершины клешней самцов синеватые, у самок красноватые.
Голубой краб имеет пять пар грудных конечностей. Передняя пара конечностей преобразована в две сильные клешни разного размера. Массивная разламывающая клешня служит для раскалывания раковин, в то время как при помощи меньшей клешни краб разрывает мягкие ткани и отправляет пищу в ротовое отверстие. Пятая пара конечностей по форме похожа на байдарочное весло и служит для плавания. Голубые крабы способны отбрасывать клешни в случае опасности. Затем потерянные конечности краб может восстановить.
Фасеточные глаза на коротких стебельках расположены непосредственно под передним краем карапакса на голове. Между глазами находятся две пары коротких и тонких антенн.
Продолжительность жизни голубого краба составляет примерно от 2-х до 4-х лет.
Первоначальная родина голубого краба — это атлантическое побережье Северной и Южной Америки. В Европе этот вид был впервые обнаружен в 1900 году. Сегодня его можно встретить на обширных территориях Балтийского и Северного морей. Он обнаружен также в Средиземном и Адриатическом морях.
Голубой краб обитает преимущественно в устьях рек и на мелководье на глубине до 36 м, зимой глубже. Он предпочитает илистое и песчаное дно.
Молодым крабам необходима температура воды от 15 до 30 °C. Взрослые животные могут вынести температуру воды до 10 °C. Личинки, в отличие от молодых и взрослых животных, требовательны к среднему значению солености, не перенося значений ниже 20 ‰.
После спаривания самки возвращаются в мелководные солёные воды, в то время как самцы остаются в устьях рек.
Большую часть времени крабы прячутся в тине или морских травах, чтобы подкараулить свою добычу или защититься от врагов. Голубой краб довольно агрессивен по сравнению с другими видами.
Голубой краб конкурирует с другими ракообразными за пищу. Это всеядное животное. Его спектр питания включает моллюсков, такие как, например, мидии, молодых ракообразных, рыб, червей, а также растения. Не брезгует питаться и падалью. При нехватке пищи животное склонно к каннибализму.
К естественным врагам голубого краба относятся красный горбыль (Sciaenops ocellatus), обыкновенный крокер (Micropogonias undulatus), американская серебристая чайка (Larus argentatus smithsonianus), различные виды цапель, а также морские черепахи.
Голубой краб считается деликатесом и вылавливается в больших количествах.
К паразитам и комменсалам голубых крабов относятся:
Они могут жить на панцире, в жаберной полости, на брюшке и внутри тела голубого краба. Большинство этих паразитов не оказывают серьёзное влияние на жизнь особи.
Голубой краб становится половозрелым в возрасте от 12 до 18 месяцев. Самки спариваются только один раз в год, непосредственно после линьки, в то время как самцы спариваются чаще.
Как все ракообразные, голубой краб периодически линяет в течение всей жизни. После линьки карапакс самки мягкий в течение короткого времени. Это время самец использует для спаривания с самкой. Самка способна довольно долгое время хранить сперму самца. Она нерестится примерно через 2 месяца после спаривания. Кладка состоит из 2 млн яиц. Нерест начинается в декабре и заканчивается в октябре, при этом пик приходится на весну и лето. После того, как самка отложит икру, яйца оплодотворяются сохранённой спермой и прикрепляются на крохотные волоски на её брюшных ножках.
Инкубационный период составляет примерно 14 дней. В течение 2-х месяцев планктонные личинки проходят 8 стадий, прежде чем приобретут внешность крабов.
Голубой краб (лат. Callinectes sapidus) — ракообразное семейства Portunidae. Впервые описан Мэри Джейн Рэтбан.
藍蟹（學名Callinectes sapidus），又名青蟹或美味優游蟹，甲殼類.是一種分佈在大西洋(乞沙比克灣)、中美洲的海岸及墨西哥灣。它們是馬里蘭州的代表甲殼類，是當地重要的漁獲。[1]
藍蟹原產於由新斯科舍至阿根廷的西大西洋。[2]它們被引進到日本及歐洲海域，也有在波羅的海、北海、地中海及黑海。[3]
藍蟹的天敵包括鰻、石首魚科、石頭魚、黃尾平口石首魚、鱒魚、一些鯊魚、人類及魟科。藍蟹是雜食性的，同時會吃植物及動物。藍蟹一般會吃雙殼綱、環節動物、小魚、植物及任何可以吃的東西，如腐屍、其他藍蟹及垃圾。[4]
藍蟹可以從其腹部來分辨雄性及雌性。雄蟹的圍邊長而窄，雌性的則闊及圓。
切薩皮克灣的藍蟹會有季節性的遷徙。在交配後，雌蟹會遷徙到切薩皮克灣南部，將從雄蟹得來的精子令卵子受精。[5]於11月或12月，雌蟹會排出卵子。幼體孵化後會在灣口漂浮4-5星期，幼蟹接著會回到灣內。[5]
在北美洲東部的藍蟹可以控制入侵的三葉真蟹數量。兩種蟹的數量是負相關的，例如在切薩皮克灣充滿藍蟹的地方並沒有三葉真蟹。[6]
切薩皮克灣充滿了藍蟹，是其重要的經濟來源。於1993年，藍蟹的漁獲就價值1億美元。但近年的數量卻在下跌[7]，於2000年就只有4500萬美元的收獲。
雖然藍蟹是當地著名的食物，但卻供不應求。大部份在馬里蘭州餐廳出售的藍蟹都被運往北卡羅來納州、路易斯安那州、佛羅里達州、阿拉巴馬州、密西西比州及德克薩斯州，很多蟹餅都是以墨西哥及委內瑞拉等地方進口的蟹肉製成。
商業捕捉藍蟹是使用蟹籠。蟹籠是以絲網製成及呈立方體。蟹籠一般有兩個入口，呈錐狀的孔口，只可讓蟹從單一方向擠入。蟹籠會放幾種肉類作餌，包括鯡魚、扁鰺、雞、鰻或蟶子。餌會放在被分隔的中央部份，籠的底部可以打開。這種設計可以吸引藍蟹經入口進入，且能阻止它們把餌吃了。籠以長直線分佈在藍蟹的棲息地，每一天會進行檢查。藍蟹會被取出，蟹籠會再次放回海中。
漁民會將藍蟹漁獲分為公蟹、未成熟的雌蟹及成熟的雌蟹。雌蟹的漁獲數量比公蟹的受更多限制。準備脫殼的藍蟹會被分別開來及放在疏水缸。這個缸一般是升高及以混凝土磚製成，大小約3x5呎，並供水入內。脫殼前腳上的粉紅色斑點會逐漸變為紅色。準備脫殼的藍蟹會按程度而分隔，目的是阻止殼較硬的藍蟹把脫殼的蟹吃掉。一旦開始脫殼，藍蟹就會將殼逼裂，並從殼中脫出。它們此時十分脆弱，新殼是凝膠狀及很薄的物質，並不能保護藍蟹。殼要硬化約需48小時。漁民會將脫殼完的蟹放入冰水中，並將次運到市場作為軟殼蟹。若處理得宜，缸中的死亡率約為10%，但若缺乏管理，死亡率可以高達50%。
休閒用的蟹籠有很多種。籠的設計可以有很多不同，共通的都是以絲網造成。蟹籠一般呈立方體或稜錐，但也有圓柱體。蟹籠的入口有不同形式，如鉸閘，當籠子上升時就會關閉。就像商業用的，蟹籠內有多種肉類為餌。餌會放在籠的中央，並可讓蟹直接到達。這種設計很易讓蟹逃走，但因檢查較頻繁（約每15-30分鐘），故可以阻止逃走的發生。
曳釣繩也可以用來捉藍蟹，其漁獲量比蟹籠多，但需要更多的設備。高階的休閒漁民或小型的商業作業也會使用此方法捕蟹。其他的休閒方法包括垂釣或深水水網。日間藍蟹會走到淺水區，故在慢行的船上也可以捉到。晚間，它們會走到較深水區，在很多地區都不準於此時捕捉。
藍蟹平均有15%的肉質，有高含量的維生素B12。只要3盎司的蟹肉就能提供全日所需的維生素。
藍蟹殼上的藍色源自多種色素，包括α蝦青蟹白。α蝦青蟹白與紅色的蝦紅素相互作用會產生藍綠色。當藍蟹被烹煮時，其α蝦青蟹白被分解，只餘下蝦紅素，故會變成紅橙色。[8]
