Also known as the coconut crab, the robber crab is the world’s biggest land crustacean. It can weigh more than 4 kg and measure up to a metre across.
Christmas Island has the world’s largest and best protected population of these gentle giants, which can live to be more than 50 years old.
They are found in most parts of the island, usually sheltering during the day and venturing out at night or on overcast days.
Robber crab climbing a palm tree. Photo: Chris Bray
Robber crabs forage on the forest floor, feeding mainly on fruits, seeds and the pith of fallen trees, especially the Arenga palm. They also scavenge at the carcasses of dead animals (including other crabs) and may prey on turtle hatchlings. Robber crabs are exceptional climbers and can often be seen slowly making their way up tree trunks or along rock faces.
They are closely related to hermit crabs. Young robbers carry empty seashells or coconuts for protection, but eventually develop a hard abdomen and no longer carry a shell.
The robber crab is named because of its habit of carrying off any foreign items it comes across – they are particularly fond of shiny objects such as pots and silverware. Christmas Islanders know all about the crabs’ thieving ways and will often hang their bag from a tree branch while camping or swimming instead of leaving it on the ground.
Many robber crabs are killed by vehicles on Christmas Island every year. Please drive carefully during your visit and always give way to crabs on the road.