SIRENS =/= MERMAIDS
And just to make it as absolutely clear as possible, allow me to include some illustrations!
In Classical Mythology, a Siren looks like this:
Or, maybe, like this (winged bird-ladies, my friends. WINGED.):
And this is what a Mermaid looks like:
So, as you can see, Sirens and Mermaids are two very, very different things. Possibly even OPPOSITE things, because what is the opposite of a fish, if not a bird?
And now you know (assuming you didn't already! -- I'm guessing a lot of you already did, but whatever! consider this a PSA.)