Showing off and the urge to survive

This is a picture of a cichlid mating area. These depressions in the sandy lake floor are made, and protected, by various species of male cichlids during their breeding seasons. They can be over a meter in diameter and perhaps 30cms deep. Considering that the average size of a cichlid is around 10 cms these circular depressions are quite a feat. Apparently they are used by male cichlids to attract, court, and then mate with their fairer counterparts. Many male cichlids also have brillant "breeding colors" during this time of year. Scientists tell us that these kinds of displays and activities are linked to the universal urge in animals to procreate and thereby ensure the survival of their genetic heritage. I pretty much buy this but its a very unsatisfying explaination. It leaves me with too many unanswered questions. Why do female cichlids apparently like meter-wide depressions? Why circles and instead of squares or rhomboids even? Why is this or that particular color pattern attractive and how did it come about? Did the fish somehow choose it (unlikely?) and if not how did it evolve? How do the males decide how big to make their depressions? Is bigger better? Or are shape and depth just as important? Do they learn to make these holes or is it just instinct?
Upon reflection, considering how tenuous the cause-effect connection is between these bizarre so-called "breeding" rituals and displays and the the will to survive, its suprising how easily most of us are actually convinced that their is one.
I mean really, how much intuituve sense does it make that small male fish dig big holes in the ground because female fish think its sexy? Not much really. But then, absent a a better explaination, I, and probably you too, do think that.
Wierd.

Showing off and the urge to survive