Stickleback fish

The stickleback fish used to only live in the ocean waters and had these spikes to keep it from being eaten - I mean, how would you swallow something with spikes? In a humongous storm millions of years ago, it must have washed into lakes and lost their spines. But there are still a tiny little remaining of it: some remaining parts of the spines, some 2 red parts on the stickleback's belly. Maybe the ones in the lake should be called "false sticklebacks."

This is a photo of the lake version of the stickleback fish.

(photo from news.bbc.co.uk)