Shield-Backed Kelp Crab

Pugettia producta





Shield-backed kelp crab (Pugettia producta) are members of the superfamily Oxyrhyncha, who mimic their environment by attaching pieces of their surroundings to themselves (3). P. producta use their claws to attach algae to seta, stiff hair like structures, near the anterior portion of the carapace (3). This behavior is more common in juvenile P. producta as seta are lost as adults (3). Algal attachment is primarily used to store algae for later consumption, rather than as camouflage (3). P. producta have slightly unusual proportions, as they are longer than they are wide (1). Males reach widths of 9.3 cm while females reach widths of 7.8 cm (2). Their smooth shells are greenish brown to maroon on the top while their underbellies are a lighter red to yellow (1). P. producta live on rocky substrate and on giant kelp, which is a major food source for them (2). They are primarily herbivorous, feeding on most species of brown and red algae, though when algae is limited P. producta have been observed to feed on anthropoids and the algae attached to itself (1)(3).


(1) Cowles, D. (2005). Pugettia producta (Randall, 1839)

(2) Gotshall, D. W. (2005). Guide to marine invertebrates: Alaska to Baja California. Monterey, CA: Sea Challengers.

(3) Mastro, E. (1981). Algal Preferences for Decoration By the Californian Kelp Crab, Pugettia Producta (Randall) (Decapoda, Majidae). Crustaceana, 41(1), 64-70.

(Photograph) (c) Kevin Hintsa, some rights reserved (CC BY-NC)


  • rocky intertidal