A rounded, hairy little crab, pale with reddish mottling and dark rather than solidly black claw tips, about 1.5 cm (0.6 in) across. It shares Pocillopora heads with the guard crabs, keeping lower in the colony where the branches thicken.
A single coral head is a stack of tenancies: a pair of guard crabs near the top defending the colony, one or more of these lower down taking mucus, a coral goby among the branches, sometimes a shrimp and a barnacle embedded in the skeleton. Working out who benefits and who merely takes has occupied reef ecologists for decades, and the honest summary is that the guard crabs earn their keep and the rest are somewhere between lodgers and mild pests. Any branching coral examined closely with a torch will show several of these residents at once.
- rounded hairy shell, pale with reddish mottling
- claw tips dark but not solidly black
- shares coral heads with guard crabs, sitting lower down
- width up to 1.5 cm
