Nutrition for the Paralithodes camtschaticus depends on what life stage the crab is in.
Larvae are planktivores, consuming phytoplankton and zooplankton. So if the environment that the larvae in is filled of abundance of these then they can survive well and grow quickly.
Small crabs are more like the adult forms, starting becoming predators which feeding on kelp, sea stars, clams, muscles, nudibranch eggs, barnacles, and molted king crab exuviae (the molted carapace).
The adult red king crabs are more active predators than the small ones, migrating to regions with higher supplies of food. As they have grown up, the pods seem not much necessary now. Furthermore, because of the carapace and large size, adults are less vulnerable by enemies, so they are able to migrate around optionally to become more solitary.
They like hunting at night. And even though they may have zooplankton time to time they are generalized as carnivores. Fish, mollusks, aquatic marine worms, aquatic crustaceans, echinoderms, sponges, barnacles, brittle stars, sand dollars, and sea urchins are all on their daily menu.
The Paralithodes camtschaticus eats its food by capturing. Only if under special circumstances will it change the way to prey, otherwise it crushes the organism with its right claw and manipulates it with its left. The red king crab then chews and shreds the food by its mouthparts, the mandibles to crush food, the maxillae to move food closer to mouth, and maxillipeds, enabling the crab to consume a variety of different organisms. What’s more they also have a complete digestive system an open circulatory system.
- Cunningham, D.T. 1969. A study of the food and feeding relationships of the Alaskan king crab Paralithodes camtschatica. Master thesis. State College, California, San Diego. 84 pp.
- Dew, C.B. 1990. Behavioural ecology of podding red king crab, Paralithodes camtschatica. Can. J. Fish. Aquat. Sci., 47(10): 1944-1958.
- Jewett, S.C., Gardner, L.A. & Rusanowski, P.M.1989. Food and feeding habits of red king crab from north-western Norton Sound Alaska Pp. 219-232, In: Proc. Intern. Symp. King Tanner crabs, Univ. Alaska Sea Grant Rep., 90-04.