A lot of creatures have many ways to different things in the dark. Weather it be for hunting, navigation, or just overall survival, but by far mt favorite is bioluminescent. When the lights go out creatures with bioluminescent take on whole new colors that make them seem like a whole new creature, and that is why creatures that glow and have exotic colors are some of my absolute favorites.
This was made by https://www.furaffinity.net/user/diorionarh/