Similarly, a 2006 analysis of cats’ tongues has shown that they do not have the taste receptors that react to sweet things. This means that cats, from lions and tigers right down to domestic felines, cannot taste anything sweet. It’s not clear why, but cats are die-hard carnivores so being able to taste sweet things might not be useful to them.In contrast, fruit flies have scent receptors that are great at picking up fruity smells, but not much else. By human standards, their sense of smell is limited, but it is well-adapted to their needs.It’s not just about eyes, ears and noses, though. We can also study how sensory signals travel through an animal’s nervous system to its brain.