Feeding physiology of the carnivorous gastropod Thais clavigera (Kuster): do they eat “soup”?

The ability to feed on suspended and dissolved organic nutrients may have been retained in predatory gastropods during evolution. The carnivorous muricid neogastropod Thais clavigera feeds on prey by boring through their shells, followed by extracellular digestion and suction of the nutrient-rich fluid of the prey's body tissues. This study reports on the effect of feeding on suspended and soluble organic nutrients (SSONs) on the survival, growth, and various physiological activities including scope for growth and glycogen stores of T. clavigera. Juvenile T. clavigera of similar shell length (23.8 ± 1.7 mm) were either starved, fed with mussel Septifer virgatus, fed with SSONs from homogenized mussel flesh (S. virgatus), or fed with both mussels and SSONs, and kept in artificial seawater (salinity: 30‰) for 50 days. Ingestion of SSONs by the animals was significant. Feeding with the “soup” (i.e., SSONs) reduced tissue wastage and improved condition index of the snails. T. clavigera fed in this manner were intermediates between the starved and the mussel-fed groups in terms of mortality, growth, food consumption, respiration, scope for growth, and glycogen content measurements. Furthermore, T. clavigera fed with both mussels and SSONs exhibited an identical energy requirement and similar values of various physiological measurements as that of those fed solely on mussel flesh. Feeding of SSONs contributed >10% of the overall energy requirement when both SSONs and mussel prey were available. The results indicate that energy from suspended and dissolved organic nutrients can contribute to the maximization of energy input in T. clavigera, which may favor better survivorship and thus lifetime fitness.