It is pretty interesting how we both used Snake as inspiration and took it in different directions. I actually thought about making some kind of action arcade game, but my previous prototype and ideas didn't really click, so I went with a puzzle approach, something I enjoy a lot.
As for your logic on designing the eels, I can see where you were going with this.
I think these might be the reasons why it didn't immediately register to me.
1. It's somewhat fast-paced, so I wasn't really given much time to get used to the game.
2. I ran into the blue ones and even the red one (not the head area) and didn't receive damage or die, which led me to thinking, "Hmm. Wonder if hitting the yellow ones would be okay." (I think it might just be me being experimental since I just try a lot of things to see what happens.)
3. Maybe the jaggedness wasn't pronounced enough to warn me. Kind of appeared fuzzy from my perspective.
I don't think adding electric particles will detract from the simplistic approach you want to preserve, but, even if you don't add it, I think players will learn to avoid them after getting hit once.
So, you're welcome and thanks again for playing my game. There is indeed room for growth for both of us.