Watermark

This picture comes from Will Roundtree, and shows the ubiquitous American Alligator from an unsettling perspective. What's interesting is the tell-tale watermark left by the tiny aquatic leaves still clinging to the alligator's head. It clearly shows just how much of the alligator is hidden underwater when the alligator's eyes, ears and nose are the only parts visible on the surface. This classic "minimal exposure profile" is what makes crocodilians so capable of disguising their true nature from their prey, and hence what makes them such efficient predators.