"We may all be netted together" - Darwin. This picture is a great way to illustrate and explain the relations/interactions within all animals. Does not necessarily relate to sexual selection, but a good representation of all Darwin theorized of.
Cats with green eyes must be rarer than those with blue, brown or yellow eyes. I never see green-eyed kitties! This kitten has the most beautiful emerald eye color I've ever seen. I could get lost in those eyes.