Sunday, September 19, 2021

Comment: Dan is away, but thinking of you...

The parrotfish were plentiful... 

Diving with a few friends at the Salt Pier

... and the weather very fine on Bonaire this past week.  

But in my post that told you I was here, I presented two small mysteries about these next photos.  

And, as expected, the ever-prescient Remmij got the identification just right.  

The top fish is a Schoolmaster snapper (Lutjanus apodus) – yellow fins, medium size, the vertical bars are absent in older adults (see also the Wikipedia entry for L. apodus).  

In the second images, the blue/gold fish is Creole wrasse  (Clepticus parrae).  

It turns out that this is a hard identification problem--the Creole wrasse Wikipedia picture is not representative.  Check out this grid of images of the Creole wrasse to see the variations: 


Look at the images if you search for images of Clepticus parrae – it’s mostly blue fish.  But they change a lot over time.  The above image (mostly blue with a yellow tail) is common, but so are entirely blue fish. – or look at the variety of colors and patterns on the ReefGuide site.  This is common among reef fish—very different appearances at different parts of life.  An article from the University of the West Indies about the life of Creole wrasses points this out:  "During the initial phase the creole wrasse is purple/blue in colour, and upon reaching the terminal phase they appear purple. Larger individuals display a wash of yellow on the lower two thirds of the body..."  

To search for these fish, you can do a Search-by-Image IF you isolate a single fish in your search (it's tough to identify an entire school, en masse).  Here's me focusing in on just one fish in the big school... 

And it will, remarkably, give you a decent first result!  

Of course, you'd go on to double check this..  Yes?  

In my case, I've been diving long enough that I can recognized the general family of the fish: the top one is clearly some kind of snapper while the bottom one is clearly some kind of wrasse.  

General point:  Learning family (or classes) like this is incredibly useful.  When you're learning to identify something, make a bit of effort to understand what the natural categories are.  That will help you tremendously when searching for a specific instance.  

As we've discussed before, finding a fish identification key is an excellent move.  You'll learn these categories (such as "wrasse"  "snapper" "trunkfish" etc.), and you'll pick up lots of fine distinctions along the way.  

So I did a search for: 

     [ fish identification key Caribbean ] 

and while there are many online keys out there, I recognized the one at as a familiar one.  

By using that key, I was able to focus in on the Creole wrasse and the Schoolmaster as the identity of the fish.  

I ALSO asked about the blue sponge in the background.  And Remmij is absolutely correct:  It's a Row pore rope sponge (Aplysina cauliformis).  I recognized it as a sponge, and did an image search for: 

     [ sponge Bonaire ] 

and quickly learned about Rope sponges.  A query modification to: 

     [ rope sponge Bonaire ] 

zeroed in quickly to the Row pore rope sponge.

Remmij - If you've got a moment, can you recount what you did to find this particular sponge?  (There are a lot of sponges out there! How did you do it??)  

Search on! 

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