Growing through a series of molts to adulthood, the Dungeness crab is common in coastal waters offshore and in estuaries. The Dungeness crab plays an important role in the food chain as predator and prey in estuarine and marine environments. Dungeness crab larvae are important food for Pacific herring, Pacific sardines, rockfish, and chinook salmon. Juvenile Dungeness crabs are eaten by starry flounder, English, and rock sole, lingcod, rockfish, sturgeon, sharks, and skates. As juveniles living in estuaries, Dungeness crab feed primarily on fish, shrimp, molluscs, and crustaceans.
Adults feed on shrimp and bivalves and are eaten by humans, harbor seals, and sea lions.
Dungeness crab are intolerant of low dissolved oxygen conditions, and even low concentrations of ammonia are toxic. Dungeness crab larvae are highly sensitive to other insecticides and fungicides as well. They are also impacted by urban pollutants such as heavy metals, PCBs, and hydrocarbons. Concentrations of these contaminants presently exist in San Francisco Bay and sublethal impacts have been observed. Found in coastal waters from Santa Barbara, California, to the Pribilof Islands, Alaska.