Here is a video which is worth watching several times and musing over. (Thanks to Hassan for recommending it.)
It starts beautifully:
“Attracting attention is an essential part of winning a mate. The world’s oceans are filled with brilliant colours, all designed to make their wearers conspicuous. Unfortunately this small Japanese puffer fish is dull…”
And it goes on even more beautifully:
The video has subtitles but if there is anything you don’t understand, feel welcome to ask.