Image of human eye from: Source Seeing is a sense that we often take for granted. Animals of all sorts have developed eyes that allow them to hunt and survive in their environment. From the early beginnings of the eye which involved a pit that could only detect light and dark, animals have evolved and solved the problem of seeing what is out there in a variety of ways. Negative lens on the left and positive lens on the right. Source . One reason that eyes likely evolved is pressures from the need to find moving prey and to avoid being eaten. In fact, we see some unique adaptations to the pressures of hunting in predator species. Eagles and hawks as well as chameleons and the sandlance, a fish species, have all developed negative lenses. Unlike our human eye lens which is fat in the middle and skinny on the edges, a positive lens, these animals have lenses that are skinny in the middle and fat on the edges. This produces a