The film shows the spontaneous migration of the crab Dotilla sulcata, up to 1 cm in size, occupying a section of beach at Al Ghardaga on the Red Sea, at the beginning of the Spring ebb tide. A mass migration takes place to the dry lower lying area which was water covered during the previous neap tides. The crabs, packed closely together, follow the retreating edge of the water. No individual distance is maintained, aggression is not obvious. The crabs finally spread throughout the water free muddy area and occupy new feeding grounds there, which they then defend against each other and where they dig holes before the next flood tide.