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Crabs coastal a guide to the crabs of New Zealand ![]() CLICK FOR DOWNLOAD --------------------------------- Classification Phylum Arthropoda Subphylum Crustacea Class Malacostraca Order Decapoda Infraorder Brachyura Family Cancridae Genus Cancer Species Cancer irroratus
.............................. CRAWFISH PRODUCTION MANUALCLICK FOR DOWNLOAD |
CANCER IRRORATUS CRAB Atlantic rock crab or peekytoe crab Cancer irroratus (common name the Atlantic rock crab or peekytoe crab) is a crab in the genus Cancer. It is found from Labrador to South Carolina at depths up to 790 m, and reaches 133 mm across the carapace. Description The rock crab's size varies considerably between males and females. A fully mature male can reach a cephalothorax width between 50mm-140mm, and range in weight from 49-202g . Cephalothorax width is measured as the distance between the two most lateral notches on the carapace . It is uncommon for females to surpass 100mm . The shape of a rock crab's shell is wide and oval. It is a yellowish color and frequently shades of red and purplish brown are visible. The different array of colors gives this creature a unique and colorful carapace. Another interesting characteristic of the rock crab is its denitition, or teeth. The rock crab has either nine broad and smooth or rough jagged teeth, depending on its diet . Habitat Cancer irroratus live in the benthic zone of the ocean . They are able to adapt to extreme variations in depth. The depths that they exist at range from deep waters at 2,600ft. to very shallow waters and occasionly well inland from the low tide line . They live on a variety of substrate types including rocky and loose material. Smaller crabs with the cephalorthorax width of about 50 mm tend to inhabit muddy or sandy bottoms, while other crabs seem to prefer the rocky bottoms . Fisheries The rock crab has recently become a popular culinary item. The coining of the name "peekytoe crab," referring to the fact that the legs are "picked" . Until about 1997, they were considered a nuisance species by the lobster industry because they would eat the bait from lobster traps. Reproduction Cancer irroratus reproduction occurs in the autumn. Before mating commences, both male and female rock crabs moult their shell. This event for males happens during the winter months to ensure that their shells are completely firm before the fall. Females moult their shells during the fall so that they remain soft during mating. It takes rock crab shells between 2-3 months to fully harden. After fertilization females lay their eggs and store them under their stomach for almost a year. Depending upon the female's size the number of eggs produced can range from 125,000 to 500,000. After this period of time the eggs hatch and between the months of June to September the larva stay in the water column. By the time autumn returns the larva that were hatched metamorphose into extremely small crabs called megalops. For the first part of their life these young crabs are extremely vulnerable to predators and water turbulance. To increase their chance for survival they remain in shallow water and at the bottom of the ocean floor for protection . Behavior Cancer irroratus does not remain in one spot for too long. As a scavenger it is extremely mobile. Each season it moves between varying depths. In the autumn, which is their season of reproduction, most rock crabs remain at shallow depths . They tend to bury themselves in rocky areas and in tide pools. Their main method of defense is to pinch if provoked. Their most important predator is the lobster. Lobsters usually consume tiny rock crabs that have just metamorphsed or crabs that are still in their larva stage. Once rock crabs reach their full size they seem to be safe from lobsters . Many times rock crabs enter lobster pots and steal bait and are captured themselves as a result .varying depths. In the autumn, which is their season of reproduction, most rock crabs remain at shallow depths . They tend to bury themselves in rocky areas and in tide pools. Their main method of defense is to pinch if provoked. Their most important predator is the lobster. Lobsters usually consume tiny rock crabs that have just metamorphsed or crabs that are still in their larva stage. Once rock crabs reach their full size they seem to be safe from lobsters . Many times rock crabs enter lobster pots and steal bait and are captured themselves as a result .
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