An army of soldier crabs ("Mictyris longicarpus") marches through (as it must appear to them) a forest of aerial roots of the mangrove "Avicennia marina". Soldier crabs roam across mudflats, feeding on detritus and the microphytobenthos. They spend the majority of their time buried in the sand, appearing at low tides to form roaming groups. Due to their behavioural and feeding ecology, soldier crabs can potentially serve as important biomarkers. An analysis of soldier crab physiology can provide information on heavy metal pollution in compromised waterways. This will prove especially useful when conventional water sampling methods cannot detect low concentrations of pollutants.