Yes, of course it does. These things have to be clear, as these are the questions the producers will be looking to satisfy.
Here is how the process works, generally speaking: you write a screenplay, and you send it out, or somehow an agent or a producer reads the hears of it. The logline is USUALLY the only thing they read to determine if they want to read the script. That's it- the logline. This is why this very site was created. This is why there are businesses that do nothing BUT create loglines for people.
My comment about the Neptune Society was partially in jest. I assumed it was a going to be an animated children's story, of sorts, then I started thinking how unique it would be to make it live action, like "Mermaid" did. My thoughts got away from me. Clearly you have your own story, already in place, and I wish you nothing but the best for it.