Northern Kelp Crab (Pugettia producta)

Description: The northern kelp crab or shield-backed crab can come in colors ranging from yellow to red to brown-black, mostly settling around dark brown or olive green. Its carapace has a smooth appearance and can grow up to 9 cm wide in males and 8 cm wide in females. It has long legs that end in sharp points that are used to cling to surfaces. Their claws also have blue ends with red tips. 

Habitat: Found in intertidal zones from southern Alaska to northern Mexico. Northern kelp crabs tend to find their home along pilings, tide pools, and hidden deep within kelp beds. 

Diet: Northern kelp crabs are nocturnal vegetarians and feed mainly on bull kelp, sea cabbage, and rockweed at night. When algae is scarce they will occasionally eat mussels, barnacles, and hydroids.

Tide Pool Tidbits:

• This type of crab is one of the easier ones to identify, as its smooth outer shell is shaped like a shield - giving it their other common name, shield-backed crab.

• Unlike other kelp crab species, the northern kelp crab keeps a clean back instead of decorating itself with algae and other organisms. If it does add any algae to its shell, it’ll be at the front rostrum (point at the front of its head) and is more as a snack for later than for decoration.

• The color of the northern kelp crab is dependent on its diet, as it differs based on the type of algae they consume. This feature gives the kelp crab a natural type of camouflage. 

Reference: Walla Walla University