Deep down in the ancestral primate brain lurks an innate fear of snakes. Something rustles in the dry grass next to where you are standing; you startle and jump away ready to flee. The reason is fairly simple the instinctively jumpy primate lives to have more offspring than the curious one who looks to see what made the rustling noise, and then the curious ones become biologists. So it comes as no surprise that even at a very young age, 3 years old, humans readily notice snakes. This is great to know, but unfortunately my students are 20-something years old (they only act like 3 yr olds) and not only have they not learned all that much, but their basic instincts seem to have been blunted as well, so my worry continues. The illustration at the link shows a nicely coiled, hood-flaired cobra against a white back ground, and who would wonder about the human ability to notice that. The real world isn't so nice, and where my research is done the snakes are really, really a lot harder to spot. Here's a nice fer-de-lance in its typical understory habitat, right under one of my study trees, and it's one heck of a lot harder to see, even for a 3-year old. Hint: the head is almost dead center at the bottom of the picture looking to your left. Can you say camouflaged?