During this time females migrate to the mouths of estuaries so that larvae may be released into high salinity waters. Land crabs have even more adaptations to prevent drying out. This may be an adaptation to low oxygen levels, since the scarlet crab lives at 1000 m, near the oxygen minimum zone. It was first seen off Egyptian waters in the 1940s, but reports of blue crab sightings in Italy, Israel, Greece, and Turkey have been made, too. This creature itself is actually very unique shellfish and with great taste, this creature has also become one … If the crab is flipped over, the shape of the folded surface of the belly (the apron) reveals the animal's approximate age and sex. More information about adaptation strategies. The scarlet king crab lives even deeper than the golden king crab, and has legs that are much thinner in respect to their length. Striped bass, red drum, catfish and some sharks depend on blue crabs as part of their diet. The blue crab's carapace (or shell) is about 7 inches (17.8 cm) wide and 4 inches (10.2 cm) long. Stowaway blue crabs on ship ballasts have even showed up in the Mediterranean. Blue crab larvae are part of the Bay’s planktonic community, serving as food for menhaden, oysters and other filter feeders. Adult male crabs live in the low-salinity waters upstream, while adult female crabs live in the higher-salinity waters near the mouth of the estuary. The blue crab's incubation time is 14-17 days, which is when the eggs are brooded. The megalopae and juvenile crabs are consumed by various fishes and birds, as well as other blue crabs. Seasonal appearance: Early spring to late fall. Thinner legs require less oxygen, hence less energy. Habitat: Shallow and brackish waters, eelgrass beds, muddy bottoms. The Blue Swimmer Crab is a popular food in Australia and is targeted and caught in large numbers by professional and recreational fishers. Florida Fish and Wildlife Conservation Commission Species Profile Blue crabs have been introduced to various international waters such as in Black Sea, Mediterranean Sea, Baltic See, European Water and Japanese water. Blue Crab (Callinectes sapidus)Color: Olive green carapace, with brilliant blue claws. Additional Resources. Blue crab larvae have a salinity requirement of at least 20 ppt, and show poor survival below this threshold. The first pair is modified as pinchers and the last four pairs are walking legs. Blue Crabs. They drink water from dew and the ground, they get it from food, and even from water vapor. Juvenile and adult blue crabs serve as food for fish, birds and even other blue crabs. The sharks, striped bass, eels, drum, whiptail stingrays, conose rays, and trout are considered as some of the natural predators of blue crabs. Description. Females have red-tipped claws. Size: Up to 9 inches long from point to point, and 4 inches from head to tail. Blue crabs are sexually dimorphic.Males are slightly larger than females and have bright blue claws. As larvae, they are vulnerable to fishes, jellyfish and other planktivores. These crabs enter estuaries as juveniles and grow quite quickly, maturing after one year. Females have red-tipped claws. Crabs are crustaceans with five pairs of legs. Blue crabs are subject to predation throughout their life cycle and are particularly susceptible when they are soft during the molting process. They also store water in their bladder, blood, and specialized pockets throughout their bodies. Facts about Blue Crabs 8: the natural predators. There, however, the crab is invasive. They are mobile predators whose salinity requirements change at different stages in their lives. Blue crabs live in estuaries along the United States' Atlantic and Gulf coasts. 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