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the Legacy continues…………………….
Gregory R. Mann, Ph.D. {ret.}

Blue Crab

“Callinectes sapidus”

Although they are called Blue Crabs, these crustaceans may vary in color from blue to olive-green. The Blue Crab is a swimming crustacean with bright blue claws and an olive-green shell. It is one of the most recognizable species in the Chesapeake Bay. Blue Crabs are immigrants from the east coast of North America, where they are common & extensively fished. They are sporadically found in the Netherlands. It is unknown whether the animals are able to reproduce here or that the larvae come from elsewhere. If you should see one, you can’t be mistaken. The Blue Crab is large, has beautiful colors, blue legs and 2 tips on the sides of its carapace. They eat everything. If food is scare, they will even eat each other. The Latin name means “tasty synchronized swimmer”.

Appearance

  • Carapace (shell) varies in color from bluish to olive-green and can reach up to 9 inches across.
  • Carapace has 9 marginal teeth on each side. The 9th tooth is strong spines.
  • Claws are bright blue. Those on mature females feature red tips.
  • 3 pairs of walking legs.
  • Paddle-shaped rear swimming legs.
  • Males have a strongly tapered abdomen or “apron” that resembles an inverted T. Mature females have a broad, rounded abdomen. Immature females have a triangular abdomen.

Habitat

  • Bottom-dwelling crustacean uses all of the Chesapeake Bay’s habitats during the course of its life.
  • Distribution varies based on age, sex & season.
  • Abundant in shallow waters & bay grass beds during warm weather. Hibernates in the deep trenches of the Chesapeake Bay in winter.
  • Males spend more time in the fresher waters of the Chesapeake Bay and its rivers, while females congregate in saltier waters.

Range

  • Found in the Chesapeake Bay and its tidal rivers year-round.
  • Range spreads from Nova Scotia to Argentina in the western Atlantic Ocean.

Feeding

  • Will feed on nearly anything it can find including clams, oysters, mussels, smaller crustaceans, freshly dead fish and plant, animal detritus.
  • Will even eat smaller & soft-shelled Blue Crabs.

Predators

  • Predators include large fish & fish-eating birds.

Reproduction and Life Cycle

  • Mate from May through October in the brackish waters of the middle Chesapeake Bay.
  • Before mating, males cradle a soft-shelled female in their legs, carrying her for several days while he searches for a protected area for her final molt. Once she molts, the pair mates. After mating, the male continues to cradle the female until her shell hardens.
  • Males eventually leave to search for another mate, while females migrate to the saltier waters of the lower bay. Females develop an external egg mass or sponge beneath their aprons.
  • Each bright orange egg mass may contain between 750,000 and 2,000,000 eggs. The egg mass darkens as the developing larvae consume the orange yolk. In about 2 weeks, larvae are released into the salty waters near the mouth of the Chesapeake Bay.
  • Currents transport Blue Crab larvae called zoea, to the ocean where they molt several times as they grow. Eventually, zoea return to the bay and other estuaries.
  • During their last larval molt, zoea metamorphose into a post-larval form called the megalops. Megalops crawl over the bay’s bottom to reach the upper Chesapeake Bay and its rivers.
  • Megalops eventually metamorphose into immature crabs, which look like tiny adults. Immature crabs molt several times before they reach maturity, about 12 to 18 months after hatching.
  • Few Blue Crabs live longer than 3 years.

Other Facts

  • The Blue Crab’s scientific name comes from the Greek words for “beautiful” and “swimmer”.
  • Male Blue Crabs are known as “jimmies” while mature females are called “sooks”.
  • Blue Crabs are one of the most important commercial and recreational catches in the Chesapeake Bay.
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