Blue Crab
Callinectes sapidus
Summary 9
Callinectes sapidus (from the Greek calli- = "beautiful", nectes = "swimmer", and Latin sapidus = "savory"), the Chesapeake blue crab or Atlantic blue crab, or simply blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.
Comprehensive description 10
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".
Distribution 11
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.
Physical description 12
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
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
Lookalikes 13
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.
Habitat 14
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).
Communication and perception 15
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
Development 16
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
Reproduction 17
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)
Link to Access Genomic Data 18
http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=6763&lvl=0
Sources and Credits
- (c) Reinaldo Aguilar, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/plantaspinunsulaosa/6777815831/
- (c) jere7my tho?rpe, some rights reserved (CC BY-NC-SA), http://farm2.staticflickr.com/1252/1219864901_af8ca64bff_o.jpg
- (c) Jose Nunez, some rights reserved (CC BY-NC-ND), uploaded by Jose Nunez
- (c) Tregua Catala Ezpera, some rights reserved (CC BY-NC), uploaded by Tregua Catala Ezpera
- (c) Brian Henderson, some rights reserved (CC BY-NC), https://www.flickr.com/photos/stinkenroboter/7634796910/
- (c) Kent McFarland, some rights reserved (CC BY-NC), http://farm5.static.flickr.com/4137/4799126150_c87c3ee790.jpg
- (c) Gianluca Stasolla, some rights reserved (CC BY-NC), uploaded by Gianluca Stasolla
- (c) Thomas, some rights reserved (CC BY-NC), http://www.flickr.com/photos/28789884@N06/3205996901
- Adapted by Emily Rose Sharkey from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Callinectes_sapidus
- Adapted by Emily Rose Sharkey from a work by (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/17570589
- Adapted by Emily Rose Sharkey from a work by (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11289747
- Adapted by Emily Rose Sharkey from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18637198
- Adapted by Emily Rose Sharkey from a work by (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11289745
- Adapted by Emily Rose Sharkey from a work by (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11289748
- Adapted by Emily Rose Sharkey from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18637202
- Adapted by Emily Rose Sharkey from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18637199
- Adapted by Emily Rose Sharkey from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18637200
- (c) Emily Rose Sharkey, all rights reserved
