Visibly different, part 39

ctenophore possibly sea walnut Mnemiopsis leidyi
Our opening image, as confusing as it is, comes with a story. While living in Florida, I was running a small fishnet (probably a bait net) through the water off of a dock trying to capture some minnows when I realized my empty net wasn’t actually empty, but contained a transparent blob. With care, I transferred this into my holding jar, recognizing that it was probably a jellyfish, and deposited it into my little saltwater tank at home. Therein, I could see that it had a complicated shape while roughly spherical, about 30-35mm in diameter. I also found that the minimal flow of the circulator was still too strong for it and it quickly got pinned against the intake pipe, so I had to shut this down. I endeavored to get decent photos of it, but what you see here is the result, not very clear.

Ha! That’s a joke, because this was easily the clearest, most transparent species I’ve ever found, initially evidenced by the fact that I had no idea it was there while I swept the net through the water after other subjects. I eventually released this one, but had another encounter the next year I believe. At that time, I was snorkeling in the Indian River Lagoon, heading away from shore into more open water, and suddenly found my vision getting blurry and spotty. It took me a moment to realize that this was because it was obscured by things in the water, and once I changed my focus much closer, I realized that I had one of these only centimeters in front of me – in fact, on looking around, it was an entire herd of them, or ‘smack’ of them, the proper term of a collection of jellyfish. With great care because I still didn’t know what species this was, I backed away and tried to avoid contact, though I was almost certain that I brushed against a couple with no ill effect.

And there would not have been, because I eventually found these were comb jellyfish, or simply comb jellies, which are not actually jellyfish but ctenophores instead. They lack venom of any kind and simply engulf their prey through an opening at one end, digest what they can, then eject the remains back out the same opening – a glorified mobile bag, as it were. Granted, nearly every other species, us included, is a glorified tube, so let’s not get high-handed here. Just barely visible in my photo, as they fall into the short focus range, are the tiny little fins that run in medians down their bodies, serving as the means of propulsion for the ctenophore – obviously, they’re not gonna chase down any dolphins. The same info source revealed that they could be bioluminescent, and so I had great reasons to capture another.

This eventually happened, but only by spotting one against a dark background where the minimal reflection of sunlight from their bodies could be discerned – seen against a sandy bottom, they vanished, and I had to shift my gaze back and forth a lot before I snagged a new specimen. Once again in my aquarium, I soon noticed that in bright light the little fins (cilia) would refract the light and send rainbow ripples down the body in a captivating manner, and of course I had to photograph this. In time, I was successful, though it took standing on a chair high above the tank and shooting directly down through the surface while the tank sat in the light coming in the window.

ctenophore possibly sea walnut Mnemiopsis leidyi showing refraction from motive cilia
I had no means of doing video at this time, which is a shame because you really should see this, but others have captured it. Despite many attempts, I saw no evidence of bioluminescence, and suspected for a while that what they actually meant was that refraction, but no, the species really can emit its own dim blue light. To the best of my knowledge, this is a sea walnut (Mnemiopsis leidyi,) which seems to be the most common species in that region.

Many years later, I had a client looking for Florida species, only in a ‘banner’ format (much wider than it was high,) and I sent along a variation of this image for consideration.

same image in banner format
Except, I never got this wide in the first place – what you saw above this was pretty close to full-frame for the one photo that showed the refraction clearly. To make it into a banner format took a lot of editing work, especially to prevent it from looking like I’d pasted everything on either side in from other portions of the same photo. I was pretty proud of the results, because even now I have to look closely to spot the repetition of certain patterns and details – I flopped, reversed, and inverted, and overdubbed more telltale details like bright points of sediment. Notice, too, that either side has its own color register, the left being more brown and the right more green, so I couldn’t swap these – I could only use right fragments on the right side. All that, and they never used that image anyway. Maybe it was more obvious than I thought…

The curious upshot of this was, I had never even tried cropping any of my images down to banner format before that client requested it, not really liking the idea, but after examining a lot of photos for the potential of such cropping, I started using it more often, and not too long afterwards chose a theme for the new blog that featured rotating banner images at top – and insisted on keeping them even as I changed themes. Though I pretty much stick to images that can be easily cropped and don’t require extensive editing work to fit.

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