In October 1959 while collecting fish from shallow waters in the lagoon near Pullamadam, about two miles from the Central Marine Fisheries Research Station, Mandapam Camp, one of us (E.G.S.) noticed sprouts of ' mud clouds' rising from the bottom at certain points. This phenomenon was repeatedly seen at certain spots five to ten metres ahead while slowly wading through the water and eventually
their origins were traced to the openings of the burrows of the ocypodid crab Macrophthalmus depressus Riippell
