Here's a pic with Sapphire, one of my Gelrien characters, practicing a dance. A Gelrien guy, who has a crush on her, is watching her practice.
The area just under the waist on female Gelriens is considered very attractive to males (I'm not sure I can call the area "hips", since Gelriens are invertebrates). This particular dance requires considerable motion with that area, and is often arousing to male Gelriens. When a male gets turned on the middle tail will turn paler in color, meaning the reproductive organs within it are active.