Figure 43.2: Interactions between Species Are Not Always Clear-Cut Ecologists long believed that the relationship between sea anemones and anemonefishes was a commensalism: that the fish, by living among the anemones’ stinging tentacles, gained protection from predators. But could it also be considered a mutualism—if the fishes’ feces provide nutrients that are important for the anemones—or competition—if the fish occasionally steal the anemones’ prey?