Originally posted by galveston75
Then if it didn't need it why and how did it go that direction and why didn't other life forms such as a trout not have that happen also. Did it not need it either or would it not help it catch food or defend itself with it? Doesn't seem to be much direction here with that process of logic.
If the eel didn't really need it then why not grow or let som ...[text shortened]... to do that as opposed to some thoughtless eel being able to recreate itself physically.
You are completely mistaken about how evolution works.
We don't grow hands or wings or penises or anything else because we need them.
Species change over time - they mutate. Most of the time these mutations are either deleterious (they kill you and life moves on without you) or benign (they do nothing and life moves on with or without you). Sometimes - very, very occasionally - a mutation does something that helps you to survive better, or have more kids. You pass this mutation on to your kids, and voila, evolution is off and running.
But what decides if a mutation is good or bad or indifferent? The environment the species lives in.
So, let's look at an example - wings. I'm not saying this is how wings developed - I don't think we truly know that. But, here's a story about how they could, which follows an evolutionary pathway.
I'll ignore birds at the moment and look at flying mammals - bats.
Let's start with some primordial rat - I think bats are related to rodents so that may not be too far off anyway. This particular rat lives in a tree, or at least uses trees to hunt or escape predators or whatever. Occasionally it jumps across from one branch to another within trees and, if they're close enough, even jumps between trees.
Alright so far?
Okay, now one day a rat is born that has a mutation - a slightly larger flap of skin in its armpit. Doesn't have to be big - you might not even notice it - but there's some small genetic mutation that's led to it having some miniscule extra skin there. And lo and behold, the skin flap helps it to jump a little bit further than its brothers and sisters. It survives better, catches more food, escapes more easily .... has more kids, all of which have this same mutation.
Time passes. Lots of time.
Generations of bats are born - many have the mutation now because it's so successful. More mutations occur - these happen all the time. Some of them make the flap of skin smaller - evolution doesn't have a direction, it goes in any direction because it's random - but some mutations make the skin flap bigger.
Hopefully you can see where I'm going with this, because this post is getting way too big.