I've put the first few entries onto the site, and I thought I'd add a little bit of behind the scenes commentary for each critter.
I had a hard time coming up with exactly how this guy works. I figured out the unique body form of the tetrabrachs, and am pretty satisfied with how that phylum had turned out. Unfortunately, I don't think I had the same stroke of originality with the planet's insectoids; at least, I doubt I'll be able to squeeze the same amount of diversity out of the body shape as terrestrial insects have done with their general body type. That said, I've managed to come up with something that is at least unique and plausible. (Still not happy with those wings, though. :) )
The general tetrabrach body shape breaks a rule that a lot of speculative biologists hold as immutable: "Eyes, mouth and brain all have to be placed at the front of the animal." Now, there are reasons that this rule should be considered, but what rule doesn't have exceptions (even on Earth)? But as I started putting aliens together for Nereus I began to realize that not only were there some that would benefit from a mouth at the front of their bodies, but that there were methods to bring it about without violating evolutionary precedent. The basker is one of these critters that has done some physiological gymnastics in order to meet design requirements. To get a better idea of what's going on with the basker, imagine your mouth is down by your stomach, and your lower jaw extends from down there all the way up to your face. Weird...
Here's another nereid that's twisted itself up to fit its design; most have a sensory stalk oriented either toward the front or straight up, but pseudocoles make use of a sensory stalk pointed straight back. While this swings the mouth to the front it also means that all of those sense organs are pointed away from fleeing prey. To counteract the deficit I decided the flag raptor used its tongues as sensitive chemoreceptors, much like the Jacobson's organ in snakes. And I didn't want to leave those eyes uselessly at the back, so I decided to throw in the visual signaling, making the flag raptor one of the most popular nereids I've made yet.
Okay, I admit I have a sickness. When I hear somebody make some statement of scientific fact I take it as a challenge to come up with an exception to refute the statement (like some of the things my teacher was telling me about Jupiter in my astrobiology class), but one that I chose to tackle with the magnificent strider was the question of size. There are all sorts of issues that come up when you have 150 tons of body mass though, and I had a lot of fun figuring it all out!
One of the aspects of the magnificent strider I discovered is that it's just too big to deal with most other life on Nereus, and I got the idea that it would probably function as an ecological feature all its own and some animals would not only benefit from its presence but would develop a symbiotic lifestyle with it. Enter the gargoyle.
Any way, that's enough patting myself on the back for now. Hope I didn't disappoint any readers with my boring commentary.