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Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 9:33 AM
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So in 2007 and 2008 I saved out all the big Blue Spotted Jawfish images I could get my hands on from www.LiveAquaria.com , specifically the Diver's Den WYSIWYG images. The premise was simple - if I could get a large enough sample size, I could conceivably search for sexual dimorphism and sexual dichromatism. Since they take pretty good "profile" shots of their fish, I thought it's very conceivable to take measurements of the head vs. the entire body to see if there's any truth to that dimorphic trait. It's tough when you're looking at one Blue Spotted Jawfish at a time, but when you can see dozens side by side, you should have a better chance seeing the differences. In the end, I had 49 images set aside! Kevin Kohen / LiveAquaria granted permission to share their watermarked images here, so credit where credit is due, these are all from the Diver's Den at www.LiveAquaria.com. These images are only redisplayed here for the purposes of this project and may only be used for the educational purposes of this project! Thanks Kevin & LiveAquaria.com! With 49 fish, you assume that there will be some of each sex in this sample. If sexual allocations are 1:1, then there should be roughly half female, half male. Of course, that may not be the case...for example if males are larger, and thus more desirable, this could be heavily skewed towards the male gender! Here's what we do know. #1. Certain times of the year Males will undergo a dramatic coloration change during courtship. #2. Supposedly, the male head is larger / bigger specifically so there's more room for mouthbrooding eggs. #3. Due to #2, some diagrams of generic jawfish have shown significant differences in the actual proportions / structure of the jaws - in these examples, things like the shape and length of the maxillaries differed substantially between the male and female fish. So...I've posted up THUMBNAILS of all 49 images in this post. In addition, the FULL RESOLUTION images are available in a .zip file - download here -> http://www.cichlidrecipe....ignals_liveaquaria.zip . If we need to discuss any particular image in greater detail, the larger originals are already on my server and can easily be linked into for display here. However, I didn't want to put all 49 full size images in the thread (it would've been a 4 mb download!) So please work with this dataset and see what you can come up with! Certainly, if you're going to measure pictures, some may not be valid. Also note, if an image shows 2 fish, it's an image of the same fish on each side....NOT a pair. Thumbnails to follow.
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 9:40 AM
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 10:08 AM
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Thanks Matt. Can't download the pics at work, but I'll review later tonight at home.
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 10:55 AM
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Matt, do think any pics of known males or known females would be helpful?
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 11:06 AM
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--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 11:21 AM
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Mike, absolutely. If anyone has extra pictures (especially if you know the sex) please post them up.
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 11:22 AM
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Andy, did you have a pair, male and female? If so, want to post up some pictures of the male and female, and offer your thoughts on sexing them?
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 1:46 PM
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I tried on three or four occasions to pair him up. That once was the only time he ever seemed interested, so my assumption is that was the only time I found him a female _or_ that was the only time I found him a female after he was of age/readiness/time of year to court. I never saw him show any signs of caring about the others (but it's a big tank) other than just petty squabbles. Oddly enough, despite the fact that it's a 28 square foot tank, at one point I had 6 jawfish (two bluespots, four pearlies) living within the same square foot. The pearlies gave me a few batches of eggs. I will go and look for photos dated around the same time as the video. My initial feel for it was just entirely random chance and this guy never helped much. He just never acted like he cared that much that any other fish was around. It's easy to tell him in photos, though. He had a cave-in accident at the LFS and had a broken jaw that mended crooked.
--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 2:34 PM
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--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 2:37 PM
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That should be a helpful video. Only males exhibit the mating colors, right? So we are pretty confident that the jaw in that video is a male.
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 2:41 PM
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 3:16 PM
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And heck, that guy is still alive. He doesn't leave his hole very often, but I can get some more photos.
--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 3:29 PM
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Okay. This is a known male. Remember that his jaw is a little screwed up.
--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 9:15 PM
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Andy, Does he seem to always have that darker, more golden yellow color and more gray body color? If you look at Matt's pictures (keeping in mind lighting) there are several that are clearly darker and more golden and others that are clearly lighter and more light yellow.
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Re:Opistignathos rosenblattii Sexing Project
Friday, August 27, 2010 9:40 PM
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Andy, a full body shot, similar in the layout to all those other fish, would be EXTREMELY helpful. That way people could take proportional measurements and start making comparisons and looking at an overall dataset.
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Re:Opistignathos rosenblattii Sexing Project
Saturday, August 28, 2010 2:37 PM
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--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Saturday, August 28, 2010 4:32 PM
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Here is a video of my bluespot. Sex is unknown, however I'm suspecting a male. Just a very early guess based on the dark coloration and the extra flaps of skin under his jam (supposedly for extra room for babies?) Hope it works, its my first attempt with youtube http://www.youtube.com/watch?v=hIPgGObsTvU
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Re:Opistignathos rosenblattii Sexing Project
Sunday, August 29, 2010 7:10 AM
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I've just been flipping through the downloaded pictures and I'm not sure I can find a clear distinguishing feature. Color seems hard to tell since the lighting and the fact that they can change color makes it unpredictable. I'm not sure I see a difference in head size. Some do seem to have a darker area behind the eyes. I'm trying to see if some have more excess skin under the jaw area, but most of these pictures don't show that. So, how hard is it to get a blue spot out of a tank if the two are the same sex?
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Re:Opistignathos rosenblattii Sexing Project
Sunday, August 29, 2010 11:56 AM
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It depends on your tank. My fish store does it all the time. I doubt I'd be able to get mine out, though.
--Andy, the bucket man. "Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886
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Re:Opistignathos rosenblattii Sexing Project
Monday, August 30, 2010 7:19 AM
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Made it out to the LFS, unfortunately they only had one bluespot in stock, so it was not much help. Looking back at Sissy's video, her male and female look identical (though you can only see the heads). I wonder if adding a bluespot in a enclosed net container or critter container will cause the bluespot that I currently have to react enough to see the color changes? Is it just the males that are supposed to change colors in defense of their homes?
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