It looks like they are vibrating. When a cat's tail shoots straight up and quivers or rattles at the tip, it is the highest form of excitement they can show. It's a Cat Tail Language 101 Cats can communicate using just their tails! From playful wiggles to graceful curls, your cat's tail has a lot to say. Uncover the secrets of your feline Purina Cat Tail Language: Why Do Cats Wag Their Tails? Moving Cat Tail, Animatronic , Wagging, 11 Moves. App Controlled! Great for Cosplay or Fursuit Tail! We Customize It for U Electric Tail Etsy