[ndr42]

Reminds me of the evolution of fish that prey on scales of other fish to have two distinct types with the mouth on the right or left:

https://en.wikipedia.org/wiki/Perissodus_microlepis

Depending on which type is more frequent the other is more successful because the prey is more cautions on the other side...

edit: spelling

[globalise83]

My comment was half in gentle jest, but you have really found a relevant example there - thanks for sharing. I guess I have a potential PhD project if I ever want to get into maritime biology: "The Dark Side of the Fish: How Crafty Parasites Outmaneuver High-Tech Pest Control"