The interior design preferences of scorpions is probably not something that crosses your mind that often. Perhaps remarkably, it hadn’t really occurred to scientists either, despite the fact that they make it a habit of theirs to ask the most wonderfully outlandish questions.
Fortunately, a team of researchers has finally decided to tackle this niche and fascinating topic in a rather ingenious way. Writing in the journal The Science of Nature, the team describe how they poured molten aluminum into vacant scorpion burrows in order to produce intricate casts of their temporary homes. 3D scans were then used to create interactive virtual models of the burrows.
“It's amazing how ubiquitous scorpion burrows are in some parts of the world, yet very little has been done to study them until now,” Lorenzo Prendini, curator at the American Museum of Natural History's Division of Invertebrate Zoology and co-author of the new study, said in a statement.
Hundreds of scorpions dig out burrows, but for this study, three from the same evolutionary family Scorpionidae were looked at, which included species from Israel and Namibia. They were removed from their burrows as the casts were made, and researchers took temperature readings at different points through the helter skelter-like sandy dwellings as they did so.
3D virtual model of a burrow, with the double spiral feature clear to see. Amanda Adams
Although each species’ burrows can be quite different from an architectural standpoint, there are three common design features that they almost invariably share.
Firstly, there is a horizontal platform near the ground surface that provides a safe place for the scorpion resident to monitor the presence of prey, predators and potential mates just outside of the burrow. They can also use this platform to warm up a little before going out and foraging for food.
Secondly, there are two spiral bends that serve one or two purposes – deterring predators from burrowing down too far, or preventing air flow from the surface and keeping the burrow relatively cool.
Lastly, there tends to be a sizeable chamber at depth, which helps keep temperatures there at a constant level. This terminal chamber allows the scorpion to shelter against incredibly high daytime temperatures, as well as a place to feed, mate, molt, and give birth.
Individual scorpions have clear preferences when it comes to their own personal burrow. Some are used as semi-permanent homes, whereas others are only lived in for a single day. Some feature spiraling tunnel networks that can be up to 2.7 meters (9 feet) long, and others have multiple entrances and are far shallower.
Significantly, scorpions are ectothermic – cold-blooded – which means that they rely on thermal energy in the external environment to regulate their internal temperature. Various features of the burrow, therefore, appear to assist the scorpion in doing this.
Apart from discovering the three aforementioned commonplace burrow design features, the team also realized that the soil composition, hardness, and moisture content strongly affected the size and shapes of the burrows. Those dug out of softer, sandier soil were often deeper than those from hard soil, as you would expect.
Metal cast of a scorpion burrow being dug out of the sand. Amanda Adams
“This work is about how burrow architecture can extend an animal's physiology by performing functions its body would otherwise have to do on its own, like maintaining a comfortable temperature or improving ventilation,” noted Berry Pinshow, a researcher at the Jacob Blaustein Institutes for Desert Research at Israel's Ben-Gurion University of the Negev, and lead author of the study, in the statement.