To make the ocean layer activity, I painted a piece of posterboard with 4 shades of blue (in theory, there should be one more for the trenches, but I skipped that for now). Then I printed off pictures of some of the animals that can be found in each layer. The backs of the pictures have a brushstroke of the same color as their layer, so that Nugget can check her work.
Top: Sunlit layer with dolphins, penguins, tuna, etc.
Second down: Twilight layer with laternfish, bristlemouth, and jellyfish
Third down: Midnight layer with anglerfish
Bottom: Abyss with tube worms, sea pig, and basket star
This was an excellent activity. She was really interested, we had some great conversations, and she was able to place everyone accurately after one demonstration. This hit her interest perfectly, because she's fascinated with/terrified of the anglerfish from Finding Nemo (she's never seen most of the movie, but we've read the book and gone on the ride at Disney).