Distribution
The range of the Dungeness crab extends from Alaska to southern California. Found on sandy and muddy bottoms, they can live from the nearshore to depths of more than 100 feet. Dungeness crab are generally abundant in Whatcom County.
Reproduction
Mating occurs between hard-shelled males and recently molted, soft-shelled females, generally in the late spring and summer. Male crabs are polygamous they mate with more than one female crab. Females store the fertilized eggs for several months under their abdomen until the eggs hatch (between February and April). Large females can carry more than 2.5 million eggs. For the first 90120 days after hatching, Dungeness crabs are freefloating planktonic larvae. Larvae settle down onto the bottom of an estuary or nearshore environment between June and September, where they molt into recognizable crabs. Crabs can molt as many as ten times in their first year.
Ecology
Dungeness are both predators and prey throughout their lives. They feed on fish, shrimp, and clams and are a food source for fish (e.g. halibut, dogfish, hake, lingcod) and octopus. Crabs will also eat other crabs. A hard shell and pincers are a crab’s main methods of defense. A hard shell is necessary to protect the crab and to function as a skeleton, but once a shell hardens, the crab cannot grow any larger. Growth can only occur with the shedding of the shell (molting). The crab will first begin to grow a soft shell and then backs out of its hard shell through a crack. Shedding the hard shell takes about 15 minutes, but it takes approximately two months for the newly developed soft shell to harden. During this period, crab are vulnerable to predators and tend to hide in the sand or mud. The crab’s newly formed shell is usually 11-29% bigger than the previous shell. A mature crab molts about once a year.