[altmanaltman]

I mean could a race of aquatic arthropods ever organize in scale enough to be a species that can travel light years and invade others? Wouldn't they just eat each other and never have any need to build a community or to colonize space?

We need to have some baseline for what we consider as "intelligent species" in this context and most intelligent species will need to have a system where they can pool their resources together towards something in a sustained social manner. This rules out a lot of social patterns such as beings that are solitary, canibalisitc and hell bent of eating each other.

[pigpop]

If you showed me a primate and I didn't have any knowledge of the existence of humans and then asked the same thing of them I'd also have to get creative about how they may evolve to be an intelligent society.