^ That's to attract potential mates.
That was actually my thinking. A space manta can travel for many hundreds of years without encountering another of its kind, so when it does, it must be as eye-catching and impressive as possible so as to ensure the propagation of the species.
thats really cool, i love things with bioluminesence.. especially real animals... you sed you got the idea from a book? which one?
The space manta is from the fiction story in the upcoming Captain's Log #40, the magazine of the Star Fleet Universe, for which this is the cover.
The Star Fleet Universe is a series of interconnected games with common ships, races, and background. It originated from Star Fleet Battles, designed by Steve Cole in the 70's, and has spawned many more games, a huge, rich background, and a steady following of players since its inception.
The Star Fleet Universe is based on TOS and TOS alone, and it is divergent from the canon Star Trek universe from TMP onward. It features many familiar races, such as Kilngons, Romulans, Tholians, and Gorn, but also features many new creations such as the Lyrans, Hydrans, and Andromedans. It has a vast and internally consistent timeline that starts in our time and goes all the way until fifty years after the end of TOS. Wars, alliances, politics, intrigue, heroes, and villains abound.
I would highly recommend you check it out.

Take a look at the link in my signature for more information.