Natural history of the Pan-American sand beach isopod Excirolana braziliensis (Crustacea: Malacostraca)

A population of the intertidal isopod Excirolana braziliensis was followed over a 10-month period at Naos Island, Panama. Average intertidal density was 2147/m² with maximum abundance occurring in the highest level. Adults were present only in the highest tidal level. Juveniles were distributed throughout all tidal levels and comprised at least 70% of the population at all times. Mean size of individuals decreased from the highest level seaward. Reproductive females were present the year round. The number of young ranged from four to 17 per brood and was dependent on the length of the female. Adults were very tolerant of changes in temperature and salinity.