Figure 1

Graphical illustration of the squid gill morphology. The 3° gill lamellae arise from the 2 order gill lamellae and create a highly folded epithelium with semi-tubular spaces. This epithelium is well perfused by blood vessels, and divided into an outer and inner epithelium lining a blood sinus re-drawn from [54]. The outer epithelium (turquois) is thin and mainly involved in gas exchange whereas the inner epithelium (orange) located in the concave areas of the third order lamellae is involved in ion regulatory processes indicated by high mitochondrial density and expression of ion transporters [11],[12].