Tick mouthparts

rjlittlefield · Post by **rjlittlefield** » Wed Jun 04, 2008 11:26 am

These are the mouthparts of a small tick, rather like the one shown in this old post.

I confess, all this anatomy is so specialized, I don't know what I'm looking at. I do know that the two big round things that look kind of like eyes aren't, and I figure those flat spines in the middle probably explain why these critters are so hard to get out, but even that much could be wrong!

Does anybody out there know how these things work?

--Rik

Technical: Canon 300D camera, Nikon 20X NA 0.40 ELWD objective at nominal extension (210 mm), 58 frames in 0.009" total stack depth (slightly under 0.0002" average focus step), HF Method A, no manual retouching. Dual fiber halogen illumination, pingpong diffuser, 2 sec/frame exposure. Crop to approximately 55% of frame width.

Charles Krebs · Post by **Charles Krebs** » Wed Jun 04, 2008 2:00 pm

Rik...
Been waiting for the first M Plan 20X shot.

So...? Working impressions...?
Looks excellent. (Amazing actually, when you consider this is a 50% crop).
I've found it (the 20X) a challenge to work with, but it can be well worth it at times.

Based on your scale bar the diameter of the small "hairs" extending upward at the top is in the neighborhood of .00012 inch (3 micron)! And we're seeing details considerably smaller than that. The smallest detail that you should be able to resolve with that objective is 0.84 micron so it would appear that you are right about there.

It's interesting to note that if you extended an f2 macro lens (like my Minolta 12.5mm f2) to provide 20X the smallest detail you could resolve would measure about 1.34 micron, and if you extended an f2.8 lens to obtain 20X the smallest resolvable detail would be 1.86 micron. We would see much less detail than you are showing us here.

As to the tick mouth parts, I have always seen images and drawings with the central part (rostrum, or hypostome) and palps extended. But those "flat spines" you refer to do indeed look like the parts along the hypostome that anchor the tick so well when it "bites". The two "holes" on either side appear to be palps that are "tucked away".

I'm not too knowledgeable about this anatomy, but it became a subject of interest for me a couple years ago. A tick bite developed a rash and I had to take the appropriate antibiotics just to be safe. Lyme disease is something I don't care to mess around with.

rjlittlefield · Post by **rjlittlefield** » Wed Jun 04, 2008 9:58 pm

Charlie, what can I say? You have excellent taste in lenses.

My first impression of this lens is that it's significantly easier to work with than I expected. DOF is quite shallow, of course, but I've worked with 20X NA 0.40 before. This lens has two big improvements, though. First is that it is sharp corner to corner, instead of having just a small sweet spot in the center like my previous basic achromat did. Second is that the working distance of this lens -- 10.5 mm -- is just the same as what I'm used to with 10X, and a whole lot more than the 3 mm of my previous 20X. Bottom line is that I'm quite pleased. Thanks again for the pointer!

About the anatomy, I think you're right. I had not considered that the animal might be able to completely withdraw both its palps and its hypostome, but that seems to explain quite nicely what I'm seeing. I still have one of these critters living in the refrigerator; perhaps I can coax it into revealing some of its secrets.

Tick bite with a rash, eh? I understand your interest. One of my friends got Lyme. It did not get detected early. The symptoms lasted a really long time. So far I've gotten off light -- only one tick has ever latched on, and he got only a brief snack before getting removed. I was impressed by the little chunk of skin that came away with the head, though!

While I had this critter under the camera, I actually snapped two stacks. Below is a stereo pair, crossed-eye.

--Rik

beetleman · Post by **beetleman** » Thu Jun 05, 2008 8:32 am

Excellent photos Rik. Very creepy in a vampire sort of way. What we need is a picture of the tick with the skin attached. A view from the bottom of the skin might show how the critter is attached.

acerola · Post by **acerola** » Thu Jun 05, 2008 1:00 pm

Nice details. It is very similar magnification than my tick head. Here the second picture. I canot not tell you if it has more detail, but you can always add more magnification with extra distance. I wonder how can it perform with the extra magnification.

rjlittlefield · Post by **rjlittlefield** » Thu Jun 05, 2008 2:51 pm

Péter, thanks for reminding of your earlier post.

Working through the relative sizes, I get that overall magnication in your second image is about 10% more than my first image in this thread. It's a bit confusing because your tick specimen is about 30% bigger than mine, but there's enough info in the scale bars to work everything out.

As I see the pictures, it seems pretty clear that the 20X objective is delivering quite a bit more detail than the 10X under these conditions.

I would expect that to be true even with more extension for the 10X, since the 10X is only 0.30 NA versus 0.40 NA for the 20X, and also the 20X has to cover only half as large a field. It would be an interesting test to run them head-to-head, but time is short and I have other things to do.

--Rik

acerola · Post by **acerola** » Thu Jun 05, 2008 3:02 pm

I read back the argument there. According to Charlie calculation the resolution limit is 0.84 micron vs 1.12 micron. I am very interested to see it side by side on the same magnification. With this two different picture it cant be judged much.

acerola · Post by **acerola** » Thu Jun 05, 2008 4:16 pm

I just read your post now, because we write our post about in the same time. My tick could be bigger indeed. And a little more detail visible on the tip of the "drill" on your picture. And I meant the third picture of my post, It has a little more detail than the second.
I just fished out another picture from another tick as tick anatomy came out here.
By the way I was also infected with Lyme disease but I found out in time for a quick antibiotic session.

rjlittlefield · Post by **rjlittlefield** » Thu Jun 05, 2008 8:22 pm

Péter, thanks for providing other ticks for comparison.

I took a closer look at the ones that I have. From playing with the live one under a dissecting scope, I was able to figure out how things fit together. Then it turned out that the dead specimen was still soft enough to manipulate, and I was able to prop it into a position that reveals the anatomy.

Here's the picture (crossed-eye stereo):

You can see in this picture that the barbed hypostome is closely surrounded by two movable parts shaped like long half-shells, pretty rigid, hinged at the base. In the live specimen, I can see that the big round hole at the end of the movable part is covered with a very flexible membrane that pulses with movement. It does not appear that anything can actually protrude from the hole.

I don't know what the movable parts are. At http://entomology.ucdavis.edu/faculty/r ... ckbio.html , the discussion says that

The mouthparts of hard ticks are readily visible from above. There are three visible components: the two outside jointed parts are the highly mobile palps; between these are paired chelicerae, which protect the center rod-shaped structure, the hypostome. The palps move laterally while the tick is feeding and do not enter the skin of the host. The rough hypostome has many beak-like projections on it.

I can only suppose that the part I have propped open is a palp, though personally I would not be inclined to call it "highly mobile". If these are the chelicerae, then I have no idea where the palps would be.

This specimen is at the edge of what I can manipulate effectively, even under a stereo scope. The black pin stuck between the mouthparts is an entomological "minuten pin". It's 10 mm long and 0.15 mm diameter. They come packaged 500 pins in a tiny envelope that looks like there's nothing in it.

By the way, this image illustrates the importance of wide aperture lenses if you want to capture fine detail. I had to open up to a marked f/2.8 to capture even this much detail -- any smaller and the image was unacceptably fuzzy. What's visible here at web resolution is pretty much all that's present in the images. Lots of empty magnification in the original pixels from the camera.

--Rik

Technical: Canon 300D with Olympus bellows lens, 20 mm f/2 at f/2.8, 1.3 sec exposure. 11-13 frames stacked at 0.001" focus step. Dual fiber halogen illuminator with tissue diffuser.
The blue background is masking tape, sticky side up, to hold the body of the tick.

acerola · Post by **acerola** » Fri Jun 06, 2008 1:13 am

Very good picture. I know the other kind has that two "highly mobile palps". I wondered how this kind works. It seemed like the whole mouth part are from just one piece (at least the surrounding "palps"). I did not try to pry them open.

Planapo · Post by **Planapo** » Fri Jun 06, 2008 8:53 am

Excellent work, Rik. A pleasure to look at it!

The earlier photos of last year you gave a link to, show a Dermacentor sp., if I am not mistaken.

Here, you have already figured out correctly what the pedipalps are and what the hypostome is.
As your pictures are taken from the ventral side of the animal one can´t see the chelicerae as - in ventral view - they should be hidden beneath the hypostome. At least this is so in Ixodes that I am more familiar with (but Dermacentor is placed in the Ixodidae too.)

Hence, you can possibly find the chelicerae like in Ixodes when looking upon the dorsal side of the hypostome.

--Betty

puzzledpaul · Post by **puzzledpaul** » Tue Jun 10, 2008 1:50 am

<< Excellent work, Rik. A pleasure to look at it! >>

Indeed - agreed - unsure what it is about the pic, but keep coming back to have another shufties ... might be the colours or the translucent nature of the hairs (presumably the halos around these are stacking artifacts?)

V. well lit.

pp

rjlittlefield · Post by **rjlittlefield** » Tue Jun 10, 2008 7:25 am

Betty, thanks for the further info and suggestions about ID. This tick has a general appearance similar to the one I shot last year, but the coloration is distinctly different. The one from last year had uniform color & pattern across the whole body. This one has a dorsal shield that is light gray, while the rest of the body is dark brown.

pp, thanks for the kind words. I find this bizarre creature a bit addictive myself. Yes, the halos around the hairs are stacking artifacts. This is one of those cases where I ran HF first because it's quick and easy, and decided that the result was good enough to stop.

--Rik

rjlittlefield · Post by **rjlittlefield** » Fri Jun 19, 2009 1:29 pm

Reviewing this topic, I noticed comments about the halos from when I ran this stack last year using Helicon Focus.

For curiosity, I reran the same stack just now using Zerene Stacker PMax. Sure enough, the halos went away, as did some stacking mush that I had not noticed earlier. As usual, there were also some changes in brightness and contrast, almost as if the lights were repositioned a bit even though it's just reprocessing the same source images.

Here is the ZS result:

As followup, see this topic: Ixodes scapularis dorsal and ventral at 5x for related pictures and a great description of how tick mouthparts work.

--Rik

lothman · Post by **lothman** » Sun Jun 21, 2009 7:37 am

Hello Rik,

excellent quality pics, can you tell me how you took the two shots for this 3D photo. Any links to get into the subject?

Regards
Lothman