Prawns were weighed and then dissected as follows. All procedures, including extractions, were performed under conditions of low-light intensity in a darkened laboratory. In most cases, and
unless mentioned otherwise, comparisons between groups of prawns were made on the pigments present in the‘prawn tail’, comprising the epidermal layer of the abdominal muscle together with the abdominal exoskeleton, including uropods and telson. This was done by removing the head and then separating the exoskeleton from the abdominal muscle. The pigmented epidermal layer was separated from the muscle taking care not to include any contents from the gastro-intestinal tract. In all cases, except for investigation of the distribution of pigment (Table 1)