Fig. 2.

Distribution of interlamellar distances for 75 fish species. The gill interlamellar distances of most fish species range from 20 to 110 μm despite immense variation in their body masses, from 10⁻¹ to 10⁵ g. We assumed that the lamellar thickness is negligible compared with the interlamellar distance, and estimated the interlamellar distance d as a reciprocal of the number of lamellae per unit length of the gill filament (2, 6). Detailed data and their sources are provided in Table S1.