A new study led by Ph.D.-degree students from Germany’s Ludwig Maximillian University and University of Rostock and co-authored by Museum Curator Lorenzo Prendini sheds light on the respiratory system of poorly understood arachnids known as solifuges—more commonly known as camel spiders. Imagery obtained through computed tomography (CT) scans shows that an amazingly efficient breathing apparatus may help these predators chase down their meals with astounding speed.
“The study is the first of its kind in 85 years,” says author Sandra Franz-Guess, a Ph.D.-degree student at Ludwig Maximillian University “It takes advantage of new technologies like micro-CT to create a more detailed picture of arachnid anatomy than was previously possible.”
Published in the journal Arthropod Structure and Development, the study found that solifuge tracheal systems consist of a remarkably complex network of breathing tubes. In the three species of Solifugae studied, the trachea branch throughout the body, delivering oxygen directly to the muscles.
To obtain this picture, solifuges were exposed to a vapor containing molecules of the element osmium, which adhered to the insides of the animal’s respiratory systems.
“This technique, in combination with computer-aided 3D reconstruction, allowed us to study the complex internal structures of these animals in unprecedented detail” says Bastian Klussmann-Fricke, an Annette Kade Fellow at the Museum's Richard Gilder Graduate School.
This efficient respiration is a boon for solifuges, better known as camel spiders. These arachnids are related to spiders, but are distinct from their cousins in numerous ways—they’re not venomous, for example, and don’t build webs. Instead, these voracious predators—some of which devour their own body weight in prey on a daily basis—chase down their meals and tear it to pieces with their massive chelicerae (jaws).
In these chases, a camel spider's speed often gives it the edge—some species have been clocked running at speeds of up to ten miles per hour. That’s significantly faster than other arachnids, no matter how quickly it seems like the spider in your bathroom moves.
That kind of speed is made possible by the tracheal system detailed in this study—a system that is absent or much simpler in more sluggish arachnids.
“In terms of their activity, these animals are more like insects than arachnids,” says Prendini. “Their respiratory anatomy reflects that.”
The study also revealed that some solifuges have air sacs inside their jaws. These light air sacs may offset the weight of their enormous jaws. The sacs might also help to operate the jaws themselves, by increasing the oxygen supply to the massive muscles used to catch, dismember, and macerate the prey into a soup that can be ingested by these hungry hunters.