The difference between Dungeness crab and Alaskan king crab is probably bigger than you think. They are both decapod crustaceans - a group that also contains lobsters, crayfish, and shrimp - and they are both found in Alaskan waters, but their similarities end there. King crabs are not true crabs, as the Dungeness crab is, but rather crab-like crustaceans. They are believed to have evolved from hermit crabs. The Dungeness crab is a single species living along the Western coast of North America, while Alaskan king crabs encompass three different species of king crab living in Alaskan waters.

Both Dungeness crab and Alaskan king crab are highly prized as delicacies. Both may be cooked by steaming or boiling, and both are low in fat and high in protein. The flesh of both Dungeness crab and Alaskan king crab are sweet and delicate.

A Dungeness crab may reach eight to ten inches (20-25 cm) in length and may be caught in many areas along the coast from Alaska to Northern Mexico. The Dungeness crab is named after a Washington town where the species was once harvested. Alaskan king crab species are much larger than Dungeness crabs.

The red king crab is the largest and most coveted of the Alaskan king crabs and said to be superior to lobster in taste. The blue king crab, sometimes marketed as red king crab, is the second largest and tastiest option, followed by the golden or brown king crab. Each type of Alaskan king crab is fished in different areas of Alaskan waters.

The Monterey Bay Aquarium's Seafood Watch lists Dungeness crab as a best choice. The crabs are caught with traps, and fishers return all females and immature males caught to the wild population. The protections that the species enjoys have led to a healthy, sustainable population.

All Alaskan king crab species are designated as a good choice, but Russian-caught king crab should be avoided. Fifty percent of Alaskan king crab populations are not overfished, but many populations are recovering from earlier decades in which king crab fishing was not well regulated. Only 10% of king crabs sold in the United States come from Alaska, but buying imported king crab is not an environmentally sound choice.