Kahalu'u and the Immature Wrasses

Orangespine Unicornfish with yellow pectoral fin

   As Sandra and I find ourselves in a period between company, we have taken advantage of our relative freedom to poke around the two local snorkeling venues.  At Kahalu'u last week I got a good look at the
Orangespine Uniconfish in its aggressive coloration, a dark black body, bright yellow forehead and the yellow pectoral fin.  That pectoral fin is the most remarkable feature; it returns to black as soon as the fish becomes less agitated.  This time I was prepared and took the picture you see here.  Sure enough, this fish bore its fancy yellow fin for only about a minute.

    We all know that fishes change colors.  In many instances its a little hard to tell why.  Black Durgons are a classic example.  They can turn on electric blue

Orangespine Unicornfish, Kahalu'u, March 2014

lines on their forehead as well as a bright orange cheek patch. But why are they doing this?   Are they excited by a food source?  Are they preparing for mating?

     In this instance, the reason is clear.  I actually see the fish that is the object of the aggression, invariably another orangespine unicornfish, being chased by the fish with the bright yellow pectoral.  Often the non-dominant fish is chased away.  In this
instance, the smaller orangespine did not leave the area, but must have produced some signal that satisfied the aggressive fish.  A dog, for example, might cower and put its tail between its legs.  In any event, the aggressor became less agitated and his pectoral fin returned in a couple seconds to black.

    On this tour of K Bay, I was pleased to see both of the immature wrasses that we think of in spring.  These are the immature of the Rockmover, the Dragon Wrasse (whose picture was featured in a recent blog)

Red Labrid Wrasse, Kahalu'u  March 2014

and the immature of the Yellowtail Coris, the Red Labrid Wrasse.  We don't have too many tulips or daffodils here in Kailua, so we have to be satisfied with these two special fish as a sign of spring.

    Immature wrasses are invariably delightful fish and Kahalu'u has its fair share.  Last summer we logged both the immature Hawaian Hogfish  (she of the fetching yellow bonnet) and the Blackstripe Coris.  We see very few adult hogfish at snorkeling depths in Kona and virtually no adult blackstripes.

   We do see the female of another wrasse, the Old Woman Wrasse (also called the Blacktail Wrasse) Thalassoma balleui, occasionally while snorkeling.  Over the past few years we have seen the immature at Kahalu'u.  She is a small but unmistakable bright green fish.  Unlike all the above wrasses, I have seen this immature in the winter, while our Canadian friends are down here snow birding.  As I thought about

Finescale Triggerfish, Kahalu'u March 2014

 about the dragon and red labrid, it occurred to me that we seem to have missed our chance for this small green wonder for this winter.

    Oh well.  There's always next year.

    On the outer reaches of my tour this day I saw a Finescale Triggerfish.  I don't believe that I have seen this fish in K Bay previously.  The finescale is now a resident at the pier and perhaps it will establish itself in more of our in shore waters.

jeff
    

Blacktail Wrasse immature November 2011  Kahalu'u