Preliminary observations on gastropod predationnaticids in the eastern Amazon

Naticid gastropods live and forage in the intermareal zone, and are commonly known to prey on bivalve mollusks. Understanding the interspecific predatory relationship of mollusks is important for the functional characterization of the trophic chain. The objective was to study the predation among the naticid gastropod Natica marochiensis on the bivalve Donax striatus. The attraction of gastropods through the locomotion of the bivalves in the substrate was evidenced, as well as a probable olfactory perception through the trails in the sediment from the locomotion of the bivalves. After the prey is perceived, gastropods gradually move on to foraging, covering the prey to suffocate it. There were no perforation marks in the bivalves consumed by N. marochiensis after the experiment. However, it was shown that large gastropods forage both small and large bivalves. Thus, the hypothesis that predatory gastropods prey on only small bivalves is refuted. In situ observations stand out that a small N. marochiensis forages D. striatus with greater body structure, but “hypothetically” by instinct it ends up despising the prey as the energy expenditure during the foraging would not be compensatory.