Table 8 Concluded . 



Species 



Common name 



Octopus bimaculoides Two-spotted octopus 



0. rubescens 



Octopus dofleini 



Red octopus 



North Pacific 

 giant octopus 



0. micropyrsus 



Cypraea spadicea Chestnut cowrie 

 Amphissa columbiana Wrinkled dove snail 

 Conus californicus California cone 



PHYLUM ARTHR0P0DA 



Panul irus interrruptus California spiny 



lobster 



Loxorhynchus grandis Sheep crab 



L_. crispatus Moss, masking crab 



Pelia tumida Dwarf crab 



Cancer antennarius Rock crab 



C. anthonyi 

 C_. jordani 

 C. productus 



Yel low crab 

 Hairy cancer crab 

 Red crab 



Lophopanopeus bel lus 



bellus Black-clawed crab 



Predatory effects 



Feeds mainly on molluscs (limpets, abalone, 

 other gastropods) and crustaceans (e.g., crabs). 



Same as above. 



Same as above. 



Found in kelp holdfasts; feeds on small 

 molluscs and crustaceans. 



Feeds on snails' eggs, anemones, ascidians. 



Common in kelp holdfasts; little known. 



Feeds on gastropods, bivalves, polychaetes 

 and others. 



Feeds on a wide variety of invertebrates. 



Feeds on molluscs and echinoderms. 



Feeds on a variety of invertebrates. 



Common in kelp holdfasts; feeds on a 

 variety of small invertebrates. 



Common around bases of kelp plants; eats a 

 variety of invertebrate prey. 



Eats a variety of invertebrate prey. 



Common in kelp holdfasts; unknown feeding. 



Eats a variety of invertebrate prey. 



Common in kelp holdfasts. 



a From North (1971b) and Morris et al . (1980), 



shores of the Pacific northwest. Because 

 of their effects, they have been called 

 "keystone species" (Paine 1966). It has 

 also been recorded that the sudden 

 intrusion of sea stars in tidepools will 

 cause the rapid exit of sea urchins, which 

 may eventually allow many species of large 

 algae to colonize (Paine and Vadas 1969). 

 The indirect effects of sea stars on algal 

 assemblages in subtidal habitats, however, 

 are less certain. 



The large sunflower star Pycnopodia 

 helianthoides (Figure 21) commonly 

 consumes sea urchins. Duggins (1983) 

 found that predation of sea urchins by 

 this starfish in Torch Bay, Alaska can 

 create short-lived patches free of 

 herbivores, which may significantly affect 

 subtidal algal assemblages. P_. 

 hel ianthoides will also eat chitons, 

 gastropods, crabs, and other sea stars. 

 Pisaster spp. (Figure 21) have a similar 



67 



