DOS,
You certainly know their habits far better than I do, and very likely it was curiosity that prompted what ended up as damage. They may have been investigating these floating plants in "their" pond, and pulling everything apart to more closely check things out.
I don't attribute paper shredding and other behaviors by our kittens as anger, but in our shock at seeing the plant and the planter components demolished, that was our take on things. Thank you for giving us a better understanding.
