Intertidal invaders: burrow design in marine bettles

Abstract The subsocial staphylinid beetle, Bledius spectabilis, digs persistent burrows, as air filled refuges from the tide, in the firm mud in the Salicornia zone of northern European intertidal saltmarshes. The size and shape of the maternal burrow is important: the narrow neck keeps out the initial stages of the tide and gives time for the female to respond by blocking the neck. Equally important may be the unblocking at low tide to allow diffusion of oxygen into the burrow. The soil permeability within dense aggregations (up to 4000 adults and larvae m-2) of beetles was almost a hundredfold greater than outside them. Current and long-lasting old