Energy dispersive X-ray analysis (EDXA) and proton induced x-ray emission (PIXE) coupled to the Oxford scanning proton microprobe (SPM) has been used to investigate the abundance and spatial distribution of inorganic elements in mandibles from the marine copepod calanus pacificus. X-ray spectra, elemental maps and point analytical data were collected. The mandible cutting edge is heavily silicified and has associated with it low levels of zinc. Chlorine, bromine and iodine are found in the lower half of the teeth and in the gum region. The mandibular blade is chitinous and low levels of phosphorous, sulphur, calcium, iron and copper are present throughout. The incorporation of zinc and halogens into the cutting edge is discussed in relation to feeding habit.