POPULATION STRUCTURE AND SHELL OCCUPATION PREFERENCE OF THE HERMIT CRAB ISOCHELES SAWAYAI IN SÃO VICENTE, SP

Abstract

This study investigated the population structure and shell occupation preference of the hermit crab Isocheles sawayai at Itararé Beach, São Vicente (SP). A total of 70 individuals were analyzed, collected during distinct seasonal periods in 2025 (rainy and dry). Manual sampling was conducted during two periods in the rainy season (May) and one in the dry season (July) at low tide. The results show that males (N=25) exhibited a greater mean body length (6.09 mm) compared to females (N=45, 5.20 mm), a pattern already reported for Crustacea Decapoda. The diversity of occupied shells was low, with a strong predominance of Stramonita haemastoma (55.72%) and Olivancillaria urceus (41.43%). This low diversity and strong preference reinforce the influence of local resource availability. Additionally, the presence of ovigerous females during the rainy season suggests a possible relationship between the reproductive cycle and seasonal environmental factors. The mean size of the population studied was lower than that recorded in other research, highlighting regional specificities. The findings contribute to the understanding of the ecology and reproductive biology of I. sawayai, corroborating previous studies while emphasizing the characteristics of the São Vicente population