Friday, December 16, 2011

Holiday Fish Colors - Merry Christmas Wrasse

You have to like the colors of the male Christmas wrasse (Thalassoma trilobatum) - the beautiful reds and greens show lots of contrast and a very bold pattern. It is easy to see how it came by it's common name.
 The real story, however, involves more than just pretty colors . Wrasses are an interesting group of fish with some serious gender flexibility. In the best known of their mating patterns they all start female, a pecking order sets up, and the top fish turns into a male. This top male stays after the others, keeping them female and thus running a tidy little harem situation. This is the situation with the male pictured above, it is a haremic male. It's bold color pattern signals its top-o-the heap status. And this mating pattern makes sense. The most fit animal does the most breeding.

Of course this is not the whole story, scientists have also found male wrasses in these groups that look like the drabber females and "sneak" in to mate. Whatever works, works.

There is also the theory that in some situations, being a top male wrasse with a bright bold color pattern is not a great thing (you can imagine why sticking out in nature is sometimes hazardous). It just does not work out, so a mixed group of male and female wrasses that look the same wins out and  you have a different breeding pattern.

Nature is confusing at times. If in blissful ignorance, people just appreciate the male Christmas wrasse for it's beautiful colors, even if for reasons that have nothing to do with the fish's reality, I am okay with that. If one goes further it just gets more interesting, but no less wonderful.



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