Gill chamber ventilation and scaphognathite movements in Crangon crangon (L.)

Buried Crangon crangon (L.) produce, anterior to their gill chambers, an inhalant and exhalant channel in the substratum. The combined shape and disposition of the maxillipeds effects separation of the inhalatory and exhalatory streams, and this channelling allows the maintenance of a posteroanteriorly directed flow of water over the gills of buried animals.Impedance techniques have been used to obtain qualitative data on the movements of scaphognathites. Reversals were identified and seen to occur particularly during burying and at the onset of walking. Reversals begin by the anterior region of the scaphognathite missing a beat, and end with the middle and anterior regions pausing.Analyses of movement patterns of individual scaphognathites show that a beat comprises equally-effective depression levation phases, but the timing sequence of the movements differs slightly from that reported in Carcinus maenas.