Abundant throughout the Solitary Islands Marine Park. In Australia recorded from northern Western Australia, northern Queensland south to Wilson's Promontory in Victoria.
Frequent intertidal sand flats in estuaries and among mangroves.
Soldier crabs start to appear as the tide falls, usually in large groups numbering thousands. When disturbed they burrow quickly into the sand, quickly disappearing. They feed on detritus in the sand, leaving small pellets of discarded sand. The carapace is light blue with the rest of the body being white, except for purple patches adjacent to the joints on the legs. Grows to about 25 mm across.
Davie, Peter. Wild Guide to Moreton Bay and Adjacent Coasts. Second Edition. Published by Queensland Museum. Vol 2, p.247.
Atlas of Living Australia website at https://bie.ala.org.au/search?q=mictyris+longicarpis. Accessed 14/11/2018.