Lucifer - do you know what natura selection is? It's that if xeno is born white the possible prey will most commonly see the alien glowing in the dark like a snowman, and run away/kill it. So therefore that white alien can't become a queen but is extinct.
White people are in fact a genemutation, and by natural selection you have better survival rates in North due the lack of Sun. So I say that the fact white people even exist is 'cos of natural selection in the north. And there's also the founder-effect etc where I wont go now...
Natural selection doesn't breed the strongest living thing (nor I consider aliens as one), it just makes sure the "survival of the fittest" comes in order. And there are no perfect organisms that doesn't go through that law. Your statement is that aliens have always been black, and there's no variation at all in the population? Then it more certainly would die in extinction, no matter what kind of ubercreature it is.
And I know Mr. Xeno will kill me after I've said that lol
So donut had a point about the evolution.
But that's the biological view. The real answer is that the creators wanted to make it a dark creature roaming at night 'cos you would just laugh at pink aliens jumping around in the Sun.
And Nikkie - don't put a label on whole clan, even some of our members can be ruthless and childish, thank you.
As for the alien vision I'm not sure if it's electromagnetic, and they actually have black scleras all over their eyes (or some other kind sense of vision we can't name). Or they could see eg. UV-light like birds to detect their prey. Colorvision would be a waste of resources in the dark.
Hmmh I could list all kind of senses found in animal kingdom which aren't part of our "5 senses" (we have in fact way more than 10 of them from balance to cold and hot spots, pressure, pain etc.). I need to ask this from my beloved pet, he knows a thing and two about aliens.
Hmmh and say "hep!" if you bothered to read all this blabbing so I know I'm not wasting my time in writing novels here lol