Snail radula in stereo, reflected light

Images taken in a controlled environment or with a posed subject. All subject types.

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rjlittlefield
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Snail radula in stereo, reflected light

Post by rjlittlefield »

I've looked at a lot of images of snail radulas over the years, but until recently I had never looked at a radula directly. For no obvious reason, I got curious about what I would see if I did.

So, I harvested some large snails from the border of our garden, extracted and prepared a radula using roughly the technique described by WalterD, and plopped it under a microscope with transmitted illumination. That produced an image very much like what we're used to seeing: a flattened view showing the teeth in outline. But what I really wanted to know about was the 3D structure, and I wasn't getting that.

So then I thought to dry the radula in its more or less natural 3D shape, by keeping the thing in liquid while I swapped water for acetone. After a few hours I pulled out the radula, let it dry, glued it to a toothpick, and looked at it with my usual macro setup.

First, here's an overview shot, shown as crossed-eye stereo pair. Height is about 4 mm on subject. The two little boxes are places that I'll show in more detail below.

Image

Now, here's a much higher magnification view of some teeth sitting at various angles. Again it's crossed-eye stereo and I strongly recommend viewing in stereo because it makes the structure much more clear.

Image

But even in a single image, it's easy to see in the image above that these are not the gloriously delicate and sharp teeth that are found on some other snails, easily located by searching the internet for sem snail radula. Instead, the teeth of this snail would be pretty much at home on a miniature stump grinder. I assume this is directly related to their ability and inclination to eat whatever is handy.

Finally, here's a view that I've certainly never seen before. This is the back side of the radula, the flexible plate that holds the quite rigid teeth. This radula is not completely cleared, so I expect that some of the darker gel is proteinaceous goo. As for the rest, I don't know much, but I'm intrigued by what appears to be a regular array of fibers holding the bases of the teeth.

Image

As usual, Wikipedia has a pretty good article on this topic: https://en.wikipedia.org/wiki/Radula .

The above images were shot with Mitutoyo M Plan Apo 5X NA 0.14 at 20 micron steps, and 20X NA 0.42 with 2 micron steps. Raynox DCR-150 tube lens to a Canon T1i camera.

For these images I used quite a bit "harder" illumination than usual, just a couple of flash units with paper diffusers mounted directly on the heads. The radula is of course that little white thing in the middle.

Image

I hope you find this interesting!

--Rik

Smokedaddy
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Post by Smokedaddy »

Interesting ... the stereo looks great.

BugEZ
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Post by BugEZ »

Interesting study Rik. The knobby bits look a bit like some of my wood working rasps, though less sharp.

The stereos are excellent!

Keith

Sumguy01
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Post by Sumguy01 »

:smt038 Very nice.
Thanks for sharing.

Olympusman
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Radula

Post by Olympusman »

Nice stereos!

Mike
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA

BugEZ
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Post by BugEZ »

Some shore flies have very raspy mouths. These scrape slime off of the rocky border of a neighborhood pond.

https://bugguide.net/node/view/664456

Regards

Keith

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Post by rjlittlefield »

BugEZ wrote:The knobby bits look a bit like some of my wood working rasps, though less sharp.
That seems a good analogy. These look like teeth of a rasp, while the more delicate ones remind me a bit of microplanes.

As for the sharpness, it's worth pointing out this section of the Wikipedia article:
These actions continually wear down the frontal teeth. New teeth are continuously formed at the posterior end of the buccal cavity in the radular sac. They are slowly brought forward to the tip by a slow forward movement of the ribbon, to be replaced in their turn when they are worn out.

Teeth production is rapid (some species produce up to five rows per day).
So, the large teeth on the upper "horizon" of the radula will be relatively old ones, probably worn from use. The ones lower in the image will be somewhat younger and presumably sharper.

As I write this, I imagine an exercise in which the radula is cut lengthwise, bisecting it, and then all the teeth along the cut are imaged in side view. Surely a task for a later time, if ever...

Thanks to all for comments about the stereo. It's a technique that I personally am very fond of, so I am pleased to hear that other people enjoy it also.

--Rik

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