The Dungeness crab (Metacarcinus magister) is one of the most economically valuable seafood species on the Pacific Coast — and one of the most important invertebrates in Alaska’s nearshore ecosystems. Named for the port of Dungeness, Washington, these crabs are both ecologically significant and the subject of one of the most carefully managed seafood fisheries in the world.
Molting: Growing Through Vulnerability
Like all crustaceans, Dungeness crabs grow by molting — shedding their rigid exoskeleton to expand before the new shell hardens. This process leaves them temporarily soft, vulnerable, and unable to defend themselves or escape predators. Soft-shell crabs actively seek protective cover during this period.
Dungeness crabs molt up to 11 times before reaching legal harvest size.
Ecological Role
Dungeness crabs are both predators and prey in Alaska’s nearshore food web:
- As predators: They consume bivalves, worms, and smaller crustaceans, controlling benthic invertebrate populations
- As prey: Important food for sea otters, octopus, halibut, and birds
The health of Dungeness crab populations is closely tied to the health of eelgrass beds, kelp forests, and the broader nearshore ecosystem. They are considered an indicator species for nearshore ecosystem condition.
At the Alaska SeaLife Center
Dungeness crabs are popular exhibit animals — their active behavior and alien appearance captivate visitors of all ages. They are also used in our education programming to demonstrate invertebrate biology, molting, and the ecological interconnections of Alaska’s coastal seas.