Fig. 7. The influence of feeding on (A) Ca and (B) Mg concentrations of the fluid phases of the gastrointestinal contents in stomach-1 (cardiac stomach), stomach-2 (pyloric stomach) and intestine in the dogfish shark. Simultaneously measured values in the blood plasma are also shown. Means ± 1 s.e.m. (N=6–8 at each time point). As points of reference, the dark bars represent the measured values for ambient seawater (SW) (N=4), and the light bars represent the measured values for the ingested food (N=5). Within a compartment, means not sharing the same letter are significantly different (P<0.05). There were no significant differences in the plasma compartment in A. In B, for clarity, x,y refers to stomach-2 and a,b to stomach-1.