Comparative Feeding Ecology of <i>Turbo intercostalis</i> (Menke, 1846) and <i>Trochus radiatus</i> (Gmelin, 1791) from the Rocky Intertidal Area of Thikkodi, Southwest Coast of India

The family Turbinidae and Trochidae are widely distributed along the rocky shore ecosystem and are considered as predominant herbivores. The main aim of the study was to analyze the gut composition and radular structure of Turbo intercostalis and Trochus radiatus. The individuals of both species were collected by random sampling method. Monthly about 20 individuals of both species were analyzed for gut contents. Scanning electron microscopy was carried out to characterize the radular structure of both species. Gut content analysis revealed that T. intercostalis consumes more macroalgae along with microalgae, but, Trochus radiatus diet composition consists of more microalgae than macroalgal content. Both species are characterized by rhipidoglossan radula. ANOSIM global test detected that the diet composition of these two species significantly differed in macroalgal composition (r=0.687, p=0.05) than diatom composition (r=0.123, p=>0.05). A total of 14 diatoms were detected in the diet composition of both species. Red macroalgal fragments were dominant in the gut of Turbo intercostalis and green fragments were more in Trochus radiatus. Food resource use within the same functional feeding guild gastropod species can be a significant factor for interaction between the species and with available food resources within a particular ecosystem.