Cute will out
Why might we find the animal on the left repulsive, while thinking the animal on the right is 'oh so cute'? Why would we run away from something ugly, but run towards something fluffy?
Photo on the left courtesy of Gary Meszaros/Photo Researchers. Source of right photo unknown.
The conscious, or subconscious, perceptions and immediate reactions we have towards animals can be explained by evolutionary thinking. Generally speaking, we want to behave in a way that's going to get our genes passed on to the next generation. This is called being "adaptive". For example, you might want to avoid predators, make sure you find a healthy mate, and protect your genetic contribution (your offspring). These kinds of adaptive behaviours may be triggered by particular features of the stimulus. In other words, the way you act towards something depends on knowing what that something is.
With these ideas in mind, we tend to have an instinctive protective mechanism towards objects (yes, even including in-animate ones!) that have "baby-like" features or are really similar to us humans. Typically, things that are short and stout, have big eyes, a large head, and short limbs. We call this 'neoteny'. A prime example is looking at how Mickey Mouse's appearance has changed over time. We see him as more appealing now because he possesses these baby-like features. In addition, animals we class as "cute" often have these features too.
The neoteny of Mickey Mouse.
What about the flip-side though? Why then, would we find certain animals ugly? Again, it comes back down to this evolutionary theory we talked about. Ugliness may represent features that are non-adaptive, for example bad genes that cause disease or deformities. This may explain why we find the star-nosed mole (above) grotesque. Similar features on a human would represent a genetic abnormality, which ultimately we would want to avoid. Finally, "ugliness" may arise from a very real fear of something dangerous. The claws of the mole, or the snake-like appearance of some lizards triggers feelings of fear or disgust which are designed to help you avoid run ins with animals that also have these features, but are much more dangerous.
It's important to point out, that "cute" and "ugly" are human constructs. Star-nosed moles would probably find each other very cute! Even so, our perception of animals is more important than we may think. Our perceptions, whether we are aware of them or not, can shape conservation and welfare efforts. Not all hope is lost though. Enthusiastic education, including the likes of Steve Irwin, can often shift our perceptions and, ultimately, our behaviour.