Infra-order Brachyura, Family Grapsidae
Intermediate grapsus | Grapsus intermedius De Man, 1888
Photo: JC Mendoza
Coloration varies through its range but on Christmas Island the crab has an overall greyish white appearance with chestnut brownish splotches. The upper surfaces and legs are covered with mottled brown/black patterning. Under surface is greyish white. Long flattened legs. The end section of the walking legs are stout and have spines.
Active at night and seldom seen during daylight. Very shy, disappearing instantly into underwater crevices at the slightest sign of danger. It is a scavenger and also eats seaweeds.
Read more about Christmas Island's intermediate grapsus crab in the book
"Crabs of Christmas Island" by Max Orchard