That prompted me to take some pictures and do some searching to see what new info would turn up since the last time I looked, now well over 10 years ago.
Some great stuff turned up, and I confess -- the main point of this post is to provide links.
But let's start with some photos...
This is the business end of what's probably an "American dog tick", Dermacentor variabilis. Crossed-eye stereo.
This is a ventral view, from underneath looking up. The picture shows three main components:
- the movable chelicerae with hooks that are used to progressively dig a hole and drag themselves into it,
- the rigid hypostome that also gets dragged into the hole, and
- one palp. Palps are sensory organs that tell the tick where to dig its hole. The palp on the other side has been dissected away for clarity from other angles.
Here are the corresponding dorsal views. This is the side where the palp was removed.
Now for the first big link: https://royalsocietypublishing.org/doi/ ... .2013.1758 , "How ticks get under your skin: insertion mechanics of the feeding apparatus of Ixodes ricinus ticks", by Dania Richter, Franz-Rainer Matuschka, Andrew Spielman and L. Mahadevan, Proceedings of the Royal Society B, 22 December 2013.
The paper itself is behind a paywall, $29.25 which I happily paid to read the full text and see all the illustrations. But it seems that the Supplemental Materials, which includes the videos and animations, are not paywalled. Those are at https://royalsocietypublishing.org/doi/ ... .2013.1758 . Some of the formats cannot be handled by standard players, but I was able to play all of them using the VLC media player (https://www.videolan.org/).Abstract
The tick Ixodes ricinus uses its mouthparts to penetrate the skin of its host and to remain attached for about a week, during which time Lyme disease spirochaetes may pass from the tick to the host. To understand how the tick achieves both tasks, penetration and attachment, with the same set of implements, we recorded the insertion events by cinematography, interpreted the mouthparts’ function by scanning electron microscopy and identified their points of articulation by confocal microscopy. Our structural dynamic observations suggest that the process of insertion and attachment occurs via a ratchet-like mechanism with two distinct stages. Initially, the two telescoping chelicerae pierce the skin and, by moving alternately, generate a toehold. Subsequently, a breaststroke-like motion, effected by simultaneous flexure and retraction of both chelicerae, pulls in the barbed hypostome. This combination of a flexible, dynamic mechanical ratchet and a static holdfast thus allows the tick to solve the problem of how to penetrate skin and also remain stuck for long periods of time.
Some of the material can also be seen at https://www.smithsonianmag.com/science- ... l-6649718/ , and by a Google image search for "insertion mechanics of the feeding apparatus of Ixodes ricinus ticks", which will take you to https://www.semanticscholar.org/paper/H ... 20b04478ca . Unfortunately I cannot find the caption for Figure 1 anywhere except in the original paper. (It is the longest caption I have ever seen -- almost half a page of fine print!)
One more extremely detailed reference: https://www.nature.com/articles/s41598-019-56811-2 , "Three-dimensional reconstruction of the feeding apparatus of the tick Ixodes ricinus (Acari: Ixodidae): a new insight into the mechanism of blood-feeding", Marie Vancová, Tomáš Bílý, Ladislav Šimo, Jan Touš, Petr Horodyský, Daniel Růžek, Adam Novobilský, Jiří Salát, Martin Strnad, Daniel E. Sonenshine, Libor Grubhoffer & Jana Nebesářová
Abstract
The different components of the mouthparts of hard ticks (Ixodidae) enable these parasites to penetrate host skin, secrete saliva, embed, and suck blood. Moreover, the tick’s mouthparts represent a key route for saliva-assisted pathogen transmission as well as pathogen acquisition from blood meal during the tick feeding process. Much has been learned about the basic anatomy of the tick’s mouthparts and in the broad outlines of how they function in previous studies. However, the precise mechanics of these functions are little understood. Here, we propose for the first time an animated model of the orchestration of the tick mouthparts and associated structures during blood meal acquisition and salivation. These two actions are known to alternate during tick engorgement. Specifically, our attention has been paid to the mechanism underlining the blood meal uptake into the pharynx through the mouth and how ticks prevent mixing the uptaken blood with secreted saliva. We animated function of muscles attached to the salivarium and their possible opening /closing of the salivarium, with a plausible explanation of the movement of saliva within the salivarium and massive outpouring of saliva.
...
Conclusions
We used X-ray microscopy that is a non-invasive technique for the 3D reconstruction of large specimens with a spatial resolution in the micrometers and SEM for specimens where resolution in nanometer scales predetermines this type of microscopy for monitoring structures that involve smaller volumes. The reconstruction of the feeding apparatus of an unfed nymph I. ricinus enables visualization of shapes and volumes of both the salivarium and the pharynx along with the attachment/position of associated structures. Using the 3D models and based on previous observations9,12,16,17,19 we animated the suction process, mainly the function of the pharyngeal valve, pumping mechanism, and process of the expulsion of saliva in an I. ricinus nymphal stage accompanied with the possible changes in volumes and shapes of organs.
Moving on, the fourth major component is the tick's feet, which as you might guess are highly specialized for their way of life.
Again this is crossed-eye stereo; the subject is one front foot.
Easily seen in the above image is the unusual structure that consists of two long claws with an adhesive pad "below" them, plus a remarkably flexible joint that allows the claws and pad to be folded back along the leg, not in contact with any surface, while the tick walks around on its "ankles".
More about this function can be read at https://www.uni-kiel.de/en/details/news ... r-foothold , which also links to a video at https://www.youtube.com/embed/86xrClNJluo .
One nice snippet from the article:
160 years after a first note by Hermann Burmeister about the ticks’ feet composition of paired, curved, tapered tarsal claws and between them a pad, the current morphological details and adhesion experiments led to new deductions on the function of ticks’ feet. “The fact that not only the pad, but also the transparent claws contain the elastic protein resilin is surprising, because we have never observed resilin in arthropod claws before,” said Dagmar Voigt from the Institute for Botany of Technische Universität Dresden. With these sticky pads, ticks are able to attach easily to smooth surfaces like human skin and glass. Depending on the situation and required power the pads can be folded and unfolded – similar to an accordion. An adhesion-mediated fluid adds to the adhesion of the pad. While walking in litter or on contaminated surfaces, ticks frequently fold back their feet and run on their tarsal-tibial joint.
Males are rather small and access the host body for copulation purposes only. Thus, their feet are smaller and attach less than females. On glass, females generate forces corresponding to more than 500-fold of their own body weight in order to ensure their safety.
To close for now, here is an overview of the beast that attacked me.
Overview with Mitutoyo M Plan Apo 2X, closer views with Mitutoyo M Plan Apo 20X, all with Raynox DCR 150 tube lens on Canon R7 camera. Synthetic stereo at +-5 degrees.
--Rik
