November 19, 2015 | David F. Coppedge

Animal Engineers Teach Physics Profs a Thing or Three

Three animals never went to the university, but they leave human PhDs struggling to catch up to their know-how.

Electrical engineers—electric eels: These doctorates in electrical engineering have mastered the fine-tuning of shock waves. “The high voltage discharge generated by electric eels is a powerful predatory weapon,” Current Biology says. “A new study shows that eels exploit basic physics to increase the voltage delivered to prey, inducing muscle fatigue that turns challenging prey items into easy targets.” The eels bend their bodies to deliver a double wallop, and their discharges are finely tuned to “remotely activate prey motor neurons, resulting in whole-body muscle contractions that cause temporary immobilization.” This is “a remarkable example of animal behavior exploiting physics of the natural world,” the authors remark. “Despite longstanding fascination with these creatures, we are just beginning to understand exactly how this weaponry works to subdue prey.”

Optical and cryptographic engineers—mantis shrimp: We’ve seen these little engineers before. They’re known for their 10,000-g hammerlike fist blows (6/13/12) and weird eyes that can detect circularly polarized light (3/31/08). Now we see them using that light for encrypted communication, a type of steganography or “hiding in plain sight.” Researchers publishing in Current Biology say,

Amazing FactsAnimals that communicate using conspicuous body patterns face a trade-off between desired detection by intended receivers and undesired detection from eavesdropping predators, prey, rivals, or parasites. In some cases, this trade-off favors the evolution of signals that are both hidden from predators and visible to conspecifics. Animals may produce covert signals using a property of light that is invisible to those that they wish to evade, allowing them to hide in plain sight (e.g., dragonfish can see their own, otherwise rare, red bioluminescence). The use of the polarization of light is a good example of a potentially covert communication channel, as very few vertebrates are known to use polarization for object-based vision. However, even these patterns are vulnerable to eavesdroppers, as sensitivity to the linearly polarized component of light is widespread among invertebrates due to their intrinsically polarization sensitive photoreceptors. Stomatopod crustaceans appear to have gone one step further in this arms race and have evolved a sensitivity to the circular polarization of light, along with body patterns producing it. However, to date we have no direct evidence that any of these marine crustaceans use this modality to communicate with conspecifics. We therefore investigated circular polarization vision of the mantis shrimp Gonodactylaceus falcatus and demonstrate that (1) the species produces strongly circularly polarized body patterns, (2) they discriminate the circular polarization of light, and (3) that they use circular polarization information to avoid occupied burrows when seeking a refuge.

Aeronautical engineers—bats: Could you land a plane upside down? Imagine a stuntman wearing a wingsuit flying into a cave and swooping up to hang from the ceiling. Bats do it routinely. A new study reported on Science Daily figured out how they perform this “aerobatic feat unlike anything else in the animal world.” First, the bats have to be built right. It’s “the extra mass in bats’ beefy wings that makes the maneuver possible.” But that’s not enough. They need to manipulate the wings right. Using high-speed cameras to film trained bats, researchers found that the bats use inertia to their advantage. They retract their wings ever so slightly on approach, and rotate a half turn as they land. These little bats taught PhDs at Brown University  a “counterintuitive” principle about flight they didn’t know. Now, the students want to see if they can get it to work on flying robots.

This is so cool. Animals teach human PhDs in physics and engineering things they didn’t know. Where do you suppose the animals got their education?


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