Marine Biology

Crab Profile King Crab



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The king crab is the largest type of crab commercially fished. There are three different species of crab commonly fished for in Alaska that are all known as king, which include the red king crab (Paralithodes camtschatica), the blue king crab (P. platypus), and the golden king crab (Lithodes aequispinus). The largest of these three species is the red king crab while the golden king crab is the smallest of these.

King crab can be found in the icy waters of the Northern Pacific Ocean near the coasts of Alaska, British Columbia, Russia, and Japan. Red king crab has also been introduced to the Artic Sea north of Norway. In Alaska, Bristol Bay is famous for its catch of red king crab, which is highly sought after by markets all over the world. 

King crab have circular to oval shaped bodies (known as the carapace), one pair of claws, and three pairs of walking legs. It is the number of walking legs that make king crab easy to identify as most other crab species have four pairs of walking legs along with one pair of claws. The claws of king crab are not equal in size as one claw is larger than the other. The larger claw is used to grasp prey or to pinch and defend itself while the smaller claw is used to tear off pieces of food when feeding. The coloring of the king crab is different depending on the species. Red king crab are a dark rusty red-orange while blue king crab have a dark cast of bluish-purple and golden king crab have a bronze cast over their lighter orange bodies. Red king crab can grow to be over 6 feet across when measured at their widest point from toe to toe and have been captured weighing up to 20 pounds.

The habitat of king crab consists of the ocean floor at depths of 100-600 feet where the crabs will spend their time searching for food. The diet of adult king crab consists of invertebrates such as plankton, mollusks, shrimp, other crab species, sea sponges, brittle stars, and small fish. The king crab is also prey to larger predators such as octopus, rockfish, halibut, sea otters, and other king crabs (adults are cannabalistic).

Gender differences between male and female king crab are easily identified. Males always tend to be larger than females and have a small triangular tail while females have a larger circular tail which is used to carry fertilized eggs. Females grow much more slowly than males and tend to live shorter lives while males have been recorded at living up to 20 years.

Males and females tend to live separately in large single sex groups. When the females are ready to mate, a pheromone attractant will signal the males to join the females. Females can only mate right after they molt and the male will usually stay with her before and after molting has occurred to ensure mating and to guard the female while she is regrowing her shell. Afterwards, the female will hold her fertilized eggs under her tail for up to 11 months before hatching.

King crab is commercially captured on a seasonal basis. Only males of a minimum carapace size of 6.5 inches can be retained. Fishing can only occur during the period of time when the king crab are not mating or molting. King crab are captured using crab pots specifically made to capture adult male king crab. The crab pots are baited with fish meat (usually herring) and are specifically designed to allow females or small male king crab to escape if accidentally captured.

Red king crab meat is especially tasty and is a favorite at seafood restaurants. The large legs yield big chunks of tender meat that has a delicious flavor and is fun to eat as the hard and spiny shells need to be cracked apart using crackers.

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.alaskankingcrab.com/king-crab-101.html
  • InfoBoxCallToAction ActionArrowhttp://www.nmfs.noaa.gov/fishwatch/species/red_king_crab.htm
  • InfoBoxCallToAction ActionArrowhttp://www.alaskankingcrab.com/king-crab-101.html
  • InfoBoxCallToAction ActionArrowhttp://bioweb.uwlax.edu/bio203/s2007/luchsing_sara/classification.htm
  • InfoBoxCallToAction ActionArrowhttp://bioweb.uwlax.edu/bio203/s2007/luchsing_sara/habitat_and_geography.htm
  • InfoBoxCallToAction ActionArrowhttp://www.nmfs.noaa.gov/fishwatch/species/red_king_crab.htm
  • InfoBoxCallToAction ActionArrowhttp://bioweb.uwlax.edu/bio203/s2007/luchsing_sara/reproduction_and_lifecyle.htm
  • InfoBoxCallToAction ActionArrowhttp://www.alaskankingcrab.com/king-crab-101.html