Beauty in Writing

For whatever reason, I have begun writing these stories (begun as in I've been doing it for a few years now). Stories about mermaids, mermen, sirens, finns, mers, whatever you want to call them, that is what I am writing. What does one call them? The more definitively I think about them, the more questions I raise. I think one of the main starting points for me is in every story, the description never quite makes sense.

Why does a mammal have scales? / Why does a fish have hair?
How do they breathe?
Do they have gills? - this would only apply if they are officially fish
Do they come up for air periodically, like a dolphin or whale?

What, officially, is the mermaid genre? Is there really a mermaid genre or are they lumped in with all shape-shifters?

There are a few common themes among mermaid tales - vanity (poems, especially), singing, sailors - but the major focus is their beauty, more specifically, lengthy descriptions of their glorious tails. So many of these stories seem reminiscent of The Little Mermaid (which I love, but I need variety in my life!).

Generally, part of the conflict involves legs vs tail, often involving a decision to change who they are to be with a love interest. This either says something about how special the love interest is or about the poor decision-making skills of the mer(maid / man).

Are people unable to relate to a beautiful creature wishing it was plain? I can't recall the last time I thought, "I wish I could be plain, instead of my extraordinary self," or felt sorry for someone who said that (not that I ever heard it).

In vampire stories, there are generally a few common themes - blood, sun, strength, immortality - and they focus on a mortal and try to protect them (usually successfully, but not always)... or eat them.

Do we identify better with a creature that is a husk of its former self, hungering for a part of its old life? A part of itself lost due to a bad choice? Who can't relate to action-based consequences?

In both however, I see a longing for humanity. A need to belong.

I think there is something more to mermaids than combs and mirrors and waiting for a ship of sailors to wreck on the rocks. I think there is something to be said about basing our opinions of another solely as a result of appearance.

After all, what is beauty? Can it be defined by a hair length, a specific symmetry of features? Are there age restrictions? Or is it something we can smell, hear, taste? Does one need daylight to know someone is attractive. If you can't see beauty in the dark, is it there at all?

There are so many questions swimming around in my head.

I can't stop thinking about mermaids.