Northern Kelp Crab, Pugettia producta 

Northern Kelp Crab, Pugettia producta. Underwater photograph taken in coastal waters off Oracas Island, Deep Harbor, Washington, August 2023. Photograph and Identification courtesy of Bob Hillis, Ivins, Utah.

General Information: The Northern Kelp Crab, Pugettia producta (Randall, 1840), is a feisty member of the Epialtidae Family of Decorator Crabs. It is also known as the Shield-backed Crab. In Mexico they are known as cangrejo kelp norteño. This species breeds year-round, with females capable of producing a new brood every thirty days.

Identification: The Northern Kelp Crab has a broad smooth carapace, with pronounced lateral spines and straight edges between the spines. Their rostrum is fairly short, with converging tips. Adults of this species may be brown to dark red on their dorsal surface, and yellow to scarlet underneath. Juveniles range from red to olive-green. Juveniles often attach a piece of algae to their rostrum, as additional camouflage. Northern Kelp Crabs are sexually dimorphic with the males reaching a maximum of 11.0 cm (4.3 inches) and the females 7.8 cm (3.0 inches) in length. The Northern Kelp Crab can be confused with the the Cryptic Kelp Crab, Pugettia richii, which is often more of a light color with spines across the carapace. As well as the Graceful Kelp Crab, Pugettia gracilis, which has white banding on the legs as well as blue tipped claws. Both have more elongated oval bodies.

Habitat and Range: The Northern Kelp Crab juveniles are found intertidally, among algae and under rocks. Adults are found offshore, usually in the kelp canopy, or on pilings or other vertical structures at depths up to 73 m (274 feet). The Northern Kelp Crab is a found along the west coast of North American and range from Chichagof Island, Alaska to Punta Asuncion, Baja California Sur. The Northern Kelp Crab is highly dependent on kelp beds for food and shelter.

Diet: The Northern Kelp Crab feed on giant kelp, barnacles, jellyfish, and other sessile organisms. In turn they are preyed upon by sea otters, sea lions, fish, and shore birds. Large adults of this species also provide homes for barnacles, including the Castrating Barnacle Heterosaccus californicus. 

Conservation status: The Northern Kelp Crab has not been formally evaluated from a conservation status.  However, they are common and and should be considered to be of Least Concern. They are edible however due to its small size it is seldom targeted by collectors.

Synonym:  Epialtus productus