Additional Resources. 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. Blue crabs are sexually dimorphic.Males are slightly larger than females and have bright blue claws. This may be an adaptation to low oxygen levels, since the scarlet crab lives at 1000 m, near the oxygen minimum zone. Florida Fish and Wildlife Conservation Commission Species Profile These crabs enter estuaries as juveniles and grow quite quickly, maturing after one year. They drink water from dew and the ground, they get it from food, and even from water vapor. 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. Land crabs have even more adaptations to prevent drying out. There are many crab behavioral adaptations for survival that this shellfish do since they need to be able to fight their predators and live in their natural habitat. The scarlet king crab lives even deeper than the golden king crab, and has legs that are much thinner in respect to their length. Seasonal appearance: Early spring to late fall. They also store water in their bladder, blood, and specialized pockets throughout their bodies. The first pair is modified as pinchers and the last four pairs are walking legs. Striped bass, red drum, catfish and some sharks depend on blue crabs as part of their diet. Blue crabs live in estuaries along the United States' Atlantic and Gulf coasts. Crabs are crustaceans with five pairs of legs. It weighs 1 to 2 pounds (0.45 to 0.9 kg) when fully grown. Blue Crab (Callinectes sapidus)Color: Olive green carapace, with brilliant blue claws. Blue crabs are subject to predation throughout their life cycle and are particularly susceptible when they are soft during the molting process. Females have red-tipped claws. There, however, the crab is invasive. Blue crabs have been introduced to various international waters such as in Black Sea, Mediterranean Sea, Baltic See, European Water and Japanese water. Thinner legs require less oxygen, hence less energy. Description. Habitat: Shallow and brackish waters, eelgrass beds, muddy bottoms. Blue Crabs. The Blue Swimmer Crab is a popular food in Australia and is targeted and caught in large numbers by professional and recreational fishers. As larvae, they are vulnerable to fishes, jellyfish and other planktivores. They are mobile predators whose salinity requirements change at different stages in their lives. During this time females migrate to the mouths of estuaries so that larvae may be released into high salinity waters. More information about adaptation strategies. Juvenile and adult blue crabs serve as food for fish, birds and even other blue crabs. Monitoring blue crab population levels and range shifts to gain knowledge on how changing conditions may be impacting crab populations is a useful first-step adaptation strategy for this species. Stowaway blue crabs on ship ballasts have even showed up in the Mediterranean. This creature itself is actually very unique shellfish and with great taste, this creature has also become one … The blue crab's incubation time is 14-17 days, which is when the eggs are brooded. Facts about Blue Crabs 8: the natural predators. Blue crab larvae have a salinity requirement of at least 20 ppt, and show poor survival below this threshold. The blue crab's carapace (or shell) is about 7 inches (17.8 cm) wide and 4 inches (10.2 cm) long. The sharks, striped bass, eels, drum, whiptail stingrays, conose rays, and trout are considered as some of the natural predators of blue crabs. Females have red-tipped claws. 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