Fig. 2: These fish are called surgeonfish because they have a sharp scalpel on both sides right before the backfin. They use it for defense. — Nikon D200, Nikkor AF-S DX 12-24mm, Little Brother Island, Red Sea, Egypt, 12 November 2011 Nikon D200; Δt=1/125 s; f=24 mm; f/5.6; ISO 200; 12 November 2011 14:02:34