UV-R mitigation strategies in encapsulated embryos of the intertidal gastropod Acanthina monodon: A way to compensate for lack of parental care

Intracapsular embryonic development in the intertidal zone exposes embryos to various stress sources characteristic of this environment, including UV-R. They require defensive mechanisms to mitigate its adverse effects. The presence of total carotenoids (TC), and mycosporine-like amino acids (MAAs) was studied in adults, in encapsulated embryos, and in the egg capsule walls of the intertidal gastropod Acanthina monodon. Oxygen consumption rates (OCR) were determined in encapsulated and excapsulated embryos exposed to photosynthetically active radiation (PAR) and PAR + UV-A + UV-B to understand if the capsule wall is a protective structure for encapsulated embryos. The results showed the presence of TC in adult pedal and gonad tissues, and in all encapsulated stages. MAAs were not detected. The physical structure of the capsule wall retained most wavelengths, being particularly efficient in the UV-B range. Excapsulated embryos exposed to PAR + UV-A + UV-B radiation increased its OCR compared to encapsulated embryos, indicating the protective character of the capsule wall.Fil: Cubillos, Victor M.. Universidad Austral de Chile; ChileFil: Salas Yanquin, Luis P.. Universidad Austral de Chile; ChileFil: Buchner Miranda, Joseline. Universidad Austral de Chile; ChileFil: Ramirez, Felipe. Universidad Austral de Chile; ChileFil: Zabala, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Marquez, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Jaramillo, Hans. Universidad Austral de Chile; ChileFil: Chaparro, Oscar R.. Universidad Austral de Chile; Chil

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

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 relation to the ontogeny of the carnivorous gastropod remain uncertain. We studied the occurrence of shifts in predatory strategies through the ontogeny of the gastropod Acanthina monodon preying on the mytilid Perumytilus purpuratus. Our results showed a direct relationship between predator 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 also occasionally 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 gastropods used the ABO to drill the center of the prey valves, where as mid-sized and large-sized snails used the radula and the labral tooth on the valve edges. Occasionally, large-sized snails also used ABO. Shifts in predatory strategies and attacked areas are influenced by the developmentand consolidation of structures involved in the attack as predator size increased. The incorporation 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 of larger prey. These patterns described evidences the gastropod's predatory behaviour in terms of energetic gain while minimizing the risk of the predator itself being preyed on.Fil: Büchner-Miranda, Joseline A.. Universidad Austral de Chile; ChileFil: Salas-Yanquin, Luis P.. Universidad Austral de Chile; ChileFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Navarro, Jorge M.. Universidad Austral de Chile; ChileFil: Cubillos, Victor M.. Universidad Austral de Chile; ChileFil: Matos, Alisson. Universidade Federal do Ceará; BrasilFil: Zabala, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Chaparro, Oscar R.. Universidad Austral de Chile; Chil