Ixodes scapularis dorsal and ventral at 5x

Graham46 · Post by **Graham46** » Thu Jun 18, 2009 1:04 pm

Here is a front and back shot of a female adult deer tick. Lens used was canon 65mm MP-E macro at 5x. Macro twin lite MT-24EX flash used with homemade diffuser. Both shot at ISO 125, 1/125 @ f/4. Each stack was 23 images and produced in ZS using PMax. Mounting pin was clonestamped out. Questions and comments welcome!

rjlittlefield · Post by **rjlittlefield** » Thu Jun 18, 2009 2:04 pm

OK, I'm puzzled.

First shot shows the palps closed, second shows them open.

How did you do that?

If you can arrange it, I'd like to see a closeup of the dorsal mouthparts with the palps open. I've seen the ventral in good detail (HERE, several sets of images), but I've not seen the dorsal view. I'm especially interested in seeing the chelicerae in detail.

--Rik

Graham46 · Post by **Graham46** » Fri Jun 19, 2009 5:37 am

Hey Rik,

Thanks for looking. The difference in position of the palps was not intentional-- The specimen had recently died, and for the first image, the palps were still closed up, but after I took a break and shot the next stack, they had slowly spread open. Now the palps are open for good, and I would be happy to shoot another shot of the mouthparts from the dorsal side. If its detail in the chelicerae youre looking for, we almost had the perfect thing for you-- Before the specimen died, it was dazed and must have thought it was biting something. We saw the chelicerae moving back and forth under the microscope at 32x! It was amazing. We quickly mounted it while it was still doing so, and set the 5D to record an HD movie through the 65mm at 5x. The movie started recording, and sure enough the tick was still biting the air.. but then there was an error writing the movie to the memory card and the whole camera froze. The movie was not saved, and the tick died shortly after. Now we know to keep an eye out for that in the future though and try again.

rjlittlefield · Post by **rjlittlefield** » Fri Jun 19, 2009 9:20 am

Movie of a tick biting -- yes, that would have been a treat!

While we're on the subject of bugs biting, do you happen to have or know of a movie of how mosquito mouthparts work?

One of my friends was asking the other day, but I couldn't find anything very detailed.

--Rik

Graham46 · Post by **Graham46** » Fri Jun 19, 2009 9:58 am

I dont know where to find a movie like that but I know some people I could ask.

Onto the mouth part pics, I have two for you. One is with the 5D with an extension tube attached to the 65mm already at 5x. Lighting is good, and shows a lot of detail, but the other was a much closer shot. The other image was shot with auto-montage using a leica microscope at 10x. It is not a crop like the first shot, the image you see was filling the frame, but since I had to make them both 800 pixels, they appear to be the same size. Hope you enjoy them!

Oh, and p.s. Rik-- I did not use Auto Montage to stack the second image-- I took the source images and stacked them in ZS

rjlittlefield · Post by **rjlittlefield** » Fri Jun 19, 2009 10:16 am

Fascinating! I had expected the chelicerae to be closer to the front of the hypostome, where they could cut a slit for the hypostome to be inserted. But in these pictures, it looks like the critter has to get the hypostome inserted to about the third barb before the chelicerae will even contact. Is that really the case, or am I missing something about how the mechanism works?

Nice pair of images, BTW. Sure illustrates how much lighting matters.

--Rik

Graham46 · Post by **Graham46** » Fri Jun 19, 2009 12:24 pm

Rik--
This is how it works, as explained to me by Tony. The chelicerae are barbed extensible erectile tissue that can alternately extend well past the tip of the hypostome. They each are hydrostatically powered by a bulb of fluid. The two bulbs lie back in the head of the tick. It is important to note that what appears to be the separate head of the tick is really only the mouthparts. The actual head is the front third of the disklike body. When the two palp sensory pits (so well imaged in your front-on view of the palps) locate thin skin with a lot of CO2 wafting up, the chelicerae begin alternately thrusting forward. The hypostome will be tipped downward to make contact with the skin. The first of the chelicerae to extend past the tip of the hypostome will pierce the skin and its barbs will lodge in the tissue. The second of the chelicerae will slide past it into the already pierced skin and lodge a bit deeper. The tick continues this action until the hypostome itself is pulled down into the deepening slit. All the while the tick is releasing anesthetic and anticoagulant compounds into the slit from its saliva. Once fully in, it releases a really remarkable cement that creates a sealing plug stuck in the skin. When you pull a tick out, it is this plug that appears to be a chunk of skin coming up with the tick.

rjlittlefield · Post by **rjlittlefield** » Fri Jun 19, 2009 12:30 pm

Great explanation -- many thanks!

--Rik