OK sure, scratch the "moon" part, make it a planet.
* I deliberately used the "prehensile" bit ( def. being "chiefly an animal’s limb or tail- capable of grasping") cause it gives a bit more leeway when imagining the creature, it only has to be flexible enough to use tools so it can look whatever one imagines it.
*As for the size I intended to put that in but it slipped my mind later on, I imagined them to be some 3m tall, and as I pointed out at the end their superior stamin should have given them an edge which would counter the low birth-rate since if you can run for long enough and fast enough your average predator will look elsewhere for an easier prey. Also I could probably add a bit which would say something about their young being in a sort of a community crèche guarded by e.g. neuters.
Quote:
Visten have always been most comfortable within the watery confinements of their home sea but have adapted and evolved into amphibians as the time progressed and their intelligence increased.
*I think this bit from the PHYSICAL DESCRIPTION part answers the question.
As for an opening sentence describing them, how about something along the lines of:
"Looks like a seahorse but flys those space fighters like a hawk"...
Oh and as for a type of planet most suited for them I'd say Earth would work fine cause it has plenty of water but still enough dry land for constructing a few cities and exploiting the land. Maybe an archipelago-like planet, but def. not an ocean world. Well, not anymore...