Naturespeak A naturalist's view of the world

April 13, 2008

A Rainbow Comes to Earth

Filed under: Uncategorized — wykes @ 8:18 pm

  On  Friday evening, an energetic spring storm swept through the region.  Like a herd of thundering bison, a tempest of wind and blinding rain rolled in and pummeled the countryside into submission. The assault passed by nearly as quickly as it began and the angry clouds were soon tamed by the rays of a brilliant sunset within a resurgent blue sky.

  A brilliant rainbow signaled the storm’s end and every single robin in the vicinity hailed normalcy’s return with a bubbling chorus. I happened to be just across the field from where this arc of color struck ground just in front of a distant woodlot.  It’s not often that you actually see the end of a rainbow.  Sure, somewhere over the rainbow is the land that we heard of once in a lullaby. We are always given the chance to go to Oz by looking over the thing, but glimpsing the elusive “end of the thing” is a much rarer opportunity. Oddly enough, I opted to take a picture rather than risk retrieving the pot of gold at its base (see above). 

  You see, I know that the rainbow’s pot ‘o gold is nothing more than a kettle of fairy dust that vanishes as soon as the fiery light beneath it is extinguished.  The brilliant colors – from red to blue, indigo, and violet -on the other hand, are funneled into the earth and soaked up by the life that lives upon it. I know this particular rainbow charged up nature’s color cells in a big way. Its colors were sapped within a matter of only a few minutes.

  Even a casual look around you will reveal where all this color goes. The Red maple flowers are exploding with the crimson and the Flicker’s breast is overflowing with the yellow. It seems that the Wood Ducks have absorbed everything else, but there is plenty left over for a relatively unknown regional beauty called the Rainbow Darter. This living rainbow is perhaps the best proof that none of heaven’s colors go to waste.

 Feast your eyes upon a Darter (see here) and you are looking at a native creature whose appearance rivals even the brightest of tropical fish. These stream dwellers are now entering into the cusp of their breeding season and the males are beginning to exhibit their brightest colors of the season. I actually took this portrait nearly a month ago, so the pictured fish wasn’t even in full regalia yet. It takes a few spring rainbows to get them fully charged.

  The scientific name of this 3 inch darter is Etheostoma caeruleum, which means “blue filter mouth.”  Let’s forget the filter part for now, but instead focus on the second part of the Latin name that refers to the bright Cerulean hue that defines them. These neon blue highlights are a Rainbow Darter specialty. From the edging on the dorsal fins (those spiny fins atop the body) to the prominent side stripes, this is the shade that makes the Rainbow “pop.”  When combined with brilliant reds and oranges, this garish color combination definitely makes a statement. That statement is, simply put, “Hey Baby!”

  Female darters have some flair, but are generally much more subdued than the males (see here). They select the brightest healthiest mates from their host of suitors and have no need of superfluous make-up. If a guy fish flashes the right colors, she sinks into the gravel and allows him to fertilize her eggs as they are laid.

  Darters are creatures of fast clean water and are adapted to the fast life of riffling creeks and small rivers. Their large pectoral (side) and pelvic (bottom) fins, combined with a streamlined shape and prominent eyes- located at the top of their head- enable them to move about and feed along the bottom current. There are dozens of darter species in the region and many of them are nearly as colorful as the Rainbow Darter, but none can quite claim equity. Fortunately this is one of our commonest Michigan species and their presence is a sure sign of good water quality.

  It is safe to conclude, then, that rainbows not only are the essence of light and hue but they are the essence of a healthy stream as well.

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