Physicists and naturalists discovered "armor" in snakes using microtomography
Jun. 12th, 2025 - Jun. 12th, 2025
An article by Czech scientists, dedicated to the first ever description of dermal armor in snakes, has made it into the 100 most downloaded articles published last year in the prestigious scientific journal Scientific Reports published by Nature in the category Earth, Environment and Ecology.
A team of experts from the Faculty of Science of Charles University, the Institute of Technical and Experimental Physics of the Czech Technical University in Prague, and the 3rd Faculty of Medicine of Charles University participated in its writing.
A fundamental role in the research was played by innovative technologies developed by a team of scientists from the Imaging Microradiography Laboratory of the Institute of Technical and Experimental Physics of the Czech Technical University in Prague (ÚTEF). This team was one of the first in the Czech Republic to start imaging with the help of micro- or nanofocus X-ray (RTG) sources, which enable 3D visualization of internal structures with a resolution of less than one micrometer. The idea to combine the efforts of physicists and natural scientists came up with the idea twelve years ago by the then dean of the 3rd Faculty of Medicine, Michal Anděl, who was already cooperating with the Institute of Animal Physiology and Pathology at that time.
It was he who drew the attention of the leading Czech expert in ethology and zoology, Daniel Frynta, to a workplace capable of taking high-resolution X-ray images. And they agreed that this technology could also be used in the study of animals. A lively collaboration soon began. Naturalists who focus on small rodents, reptiles and amphibians often bring back unknown or little-known species from expeditions, and scientists from the Institute of Animal Physiology and Pathology help them study their morphology with the help of microtomography.
"One of the determining parameters for recognizing a species can be the structure of the animal's skeleton or teeth. And there are two ways to examine it: either disrupt the soft tissues and essentially destroy the collection specimen, or use microtomography, which can do this non-invasively," explains ÚTEF researcher Jan Dudák.
To obtain 3D X-ray images of animals, a team of physicists from ÚTEF uses self-adapted systems and equipment. “We literally built the first prototypes of imaging systems on our knees. When the laboratory was founded, there were no similar devices available on the market. Today, the situation is different. You can simply buy a CT system: then you just need to insert a sample into it, press a button, and you will receive an SMS that the 3D scan is ready. But thanks to the fact that we put the systems together ourselves, they are much more flexible and we are able to push them to the limits – for example, easily adjust them to different sizes and types of samples. Our original devices may not be as fast and elegant, but the fact that we develop them ourselves forces us to understand them really well,” says Jan Žemlička, one of the co-authors of the successful article.
Using original technologies, a joint team of naturalists and physicists managed to make a discovery that aroused interest all over the world. In the tails of four species of Eryx pythons, they identified the so-called osteoderms – small bony structures embedded in the skin that strengthen the snake’s tail and function similarly to armor when attacked by a predator.
“Osteoderms are relatively common in various species of lizards – monitor lizards, gerrosaurs, skinks and koalas. So I wondered why snakes, which are also scaly reptiles, couldn’t have such armor,” recalls zoologist Petra Frýdlová, recalling the beginnings of the research. According to her, it is surprising that osteoderms in snakes were not discovered long ago. Microtomography has been experiencing a boom in the last ten years, and digital repositories such as DigiMorph have CT scans of a large number of species, not just snakes. However, as she points out, the animal bodies are usually scanned in their entirety, the images are not very high quality and the osteoderms are simply not visible on them.
On the other hand, the team of the microradiography laboratory of the Institute of Telecommunications Engineering, with the help of its equipment, can obtain a 3D model of the animal in such a resolution that it is possible to recognize and even visually isolate the barely millimeter-sized bone plates in the snake tissue without any difficulty.
"Colleagues from the Faculty of Science specify the sample and we help them with its visualization. In addition to creating the 3D data, we also help to sort it and, to a certain extent, objectively analyze it. Because for someone who is not used to it, it is complicated work. And when processing the data, we sometimes come across something atypical or surprising," explains Jan Žemlička, the part of the Institute of Telecommunications Engineering laboratory in the joint research.
The advantage of microtomography is not only the excellent resolution of the image, but also the overall greater flexibility of the research. As part of the project, the team relatively easily scanned 68 specimens belonging to 27 species of snakes from different families.
"If we tried to analyze the presence of osteoderms using classical histology, it would be incomparably more time-consuming. It is also essential that the technology used is not destructive. For example, we can borrow rare samples from the 19th century from the National Museum, which, for understandable reasons, they would never allow us to study invasively. And with the help of micro-CT, we can scan them and return them to their original state," explains Petra Frýdlová.
But even so, according to her, a little luck was also needed to discover osteoderms in snake tails. “There are approximately four thousand species of snakes, and I found osteoderms in the first one I examined with the help of micro-CT. I was happy about it, of course! But it was not a complete coincidence either. I had already observed these bone formations on the surface of boas. We have these snakes in our experimental breeding at the Faculty of Science. While handling them, I noticed that they had very rough, granulose skin on their tails, and it occurred to me that these could be miniature bone formations incorporated into the skin,” says Petra Frýdlová.
According to her, it is not yet entirely clear what the newly discovered osteoderms actually serve in snakes. The most frequently mentioned function is defense against predators. But with the help of “armor”, the snake can also protect itself from its prey itself or from anyone who comes to its aid.
“The pythons we are studying live buried in the substrate and feed on young rodents that search in underground burrows. So it can easily happen that the parents of these endangered young ones find the snake's tail sticking out of the burrow and attack it,” explains Petra Frýdlová.
Several facts indicate that strong predation pressure is exerted on the tail of pythons. Their tail is completely filled with vertebrae, which are greatly enlarged and fill almost the entire volume of the tail. It is therefore strengthened both on the surface with osteoderms and from the inside with modified vertebrae. In addition, the tail is shaped similarly to the head and the snakes perform characteristic movements with it, with which they try to confuse the predator and attract it to a less sensitive part of the body.
The team members from the Institute of Telecommunications and the Faculty of Science are proud that they have managed to discover something completely new and revolutionary. With the help of microtomography, zoology today tends to verify long-known facts. Whereas the discovery of osteoderms has opened a wide field for further research: it can be assumed that there are more “armored” snakes and they still need to be discovered.
Written by Jan Machonin
September 2, 2024
Snakes
Eryx_conicus2
Eryx_miliaris