I really like the art and sound, and I was impressed you included two modes.
The puzzles were kinda cool, but felt a little loose after the first one. It seemed like I didn't have to worry about most of the obstacles.
Arcade mode mostly involved placing all of my critters really quickly? With enemies popping in and out all the time it was hard to come up with much strategy. Maybe having set obstacles from the start would make each level feel more intentional (you could consider sacrificing one type to let a breeding pair through, for example).
Overall, it was fun!