Ontogenetic Shifts of Predatory Strategies by the Carnivorous Gastropod Acanthina monodon (Pallas, 1774)

BÜCHNER-MIRANDA, JOSELINE A.; SALAS-YANQUIN, LUIS P.; AVERBUJ, ANDRES; NAVARRO, JORGE M.; CUBILLOS, VICTOR M.; MATOS, ALISSON; ZABALA, SOLEDAD; CHAPARRO, OSCAR R.

MALACOLOGIA

INST MALACOL

Año: 2021 vol. 64

0076-2997

Predatory strategies used by carnivorous gastropods may change during their ontogeny. Inmuricid gastropods attack mechanisms include an accessory boring organ (ABO), radula, labraltooth and/or pedal muscle. However, these mechanisms and their patterns of use in relationto the ontogeny of the carnivorous gastropod remain uncertain. We studied the occurrenceof shifts in predatory strategies through the ontogeny of the gastropod Acanthina monodonpreying on the mytilid Perumytilus purpuratus. Our results showed a direct relationship betweenpredator and prey size. During attack, the small-sized snails (up to 18 mm shell length, SL)used exclusively the ABO, and medium-sized snails (18?20 mm SL) shifted to using the radulafor rasping shells. Meanwhile, the largest-sized snails (> 20 mm SL) used the radula, but alsooccasionally the pedal muscle and labral tooth, to attack their prey. The site selectivity on themytilid shell varied according to predatory mechanisms used. The small-sized gastropodsused the ABO to drill the center of the prey valves, whereas mid-sized and large-sized snailsused the radula and the labral tooth on the valve edges. Occasionally, large-sized snails alsoused ABO. Shifts in predatory strategies and attacked areas are influenced by the developmentand consolidation of structures involved in the attack as predator size increased. Theincorporation of trace elements during rachidian teeth growth may enable major resistance tofriction against carbonate prey valves, as well as the appearance and development of the labraltooth, play relevant roles in the predatory mechanism shifts, which allows the consumption oflarger prey. These patterns described evidences the gastropod?s predatory behaviour in termsof energetic gain while minimizing the risk of the predator itself being preyed on.