The ecology of the following pagurid and brachyuran decapods on Aldabra is described briefly: Coenobita rugosus, C. perlatus, C. clypeatus, Birgus latro, Geograpsus stormi, G. grayi, Grapsus tenuicrustatus, Cardisoma carnifex, C. frontalis, Ocypode cordimana, O. ceratopthalma. Cardisoma carnifex and Birgus latro are the only species which range far from the shore. C. carnifex occurs in very large numbers, especially around freshwater pools. It is largely a detritus feeder. Birgus latro is also common and, though partly predaceous, is often associated with Pandanus, the fruit of which it eats. Coenobita rugosus feeds on the faeces of giant tortoises on the dunes.