Infra-order Brachyura, Family Gecarcinidea
Brown crab | Epigrapsus politus Heller, 1862
A small crab with a carapace up to 20 mm wide. Dark chocolate brown above and lighter brown/grey underneath. Dark eyes on short eye stalks. Lighter brown / purple legs. Males sometimes have one claw larger than the other. Has dense mats of hair on both sides of the mouth parts.
Found in the intertidal zone to 5 metres above sea level. Usually found under rocks, logs and leaf litter at the boundary of the beach sand or rubble and the start of the terrace forest soil.
Read more about Christmas Island's brown crab in the book
"Crabs of Christmas Island" by Max Orchard