Harbor seals are predatory juggernauts of the deep blue. A stimulating experiment uncovered the marine animal’s prey-sensing abilities, highlighting that a blindfolded seal can track an object for 30 seconds after the start of the encounter.
The star of the Awkward Moment Seal meme and its other 18 identifiable relatives have been doing this for thousands of years using their long whiskers. In order to survive in the salty free-for-all that is the ocean, the speedy swimmers rely on these highly sensitive sensors to detect fish and other moving objects before other marine residents can snatch them.
For decades, biologists have been stumped by the enigma surrounding the facial antennas of seals. Recently, for the first time, engineers from MIT revealed the true mechanics behind the whiskers through artificial models. Using intricate 3D-printing techniques, the group created scaled replicas of the sensory appendages.
Hidden, Slaloming-like Capabilities
The study, which was published in the Journal of Fluid Mechanics, shined light on the composition of the whiskers. Prior to the research, scientists assumed that the long protrusions were straight and smooth. But a closer look revealed a wavy shape “with an elliptical cross-section that varies in size along its span,” giving it the ability to vibrate at the same frequency of nearby moving objects (or a potential meal).
“The geometry of the whisker allows for this phenomenon of being able to move very silently through the water if the water’s calm, and extract energy from the fish’s wake in order to vibrate a lot,” said Heather Beem, one of the researchers from the study. “Now we have an idea of how it’s possible that seals can find fish that they can’t see.”
Surprisingly, this method isn’t limited to location. Seals also use the same technique to determine the size, shape and path of various prey. Like big data computing, it is likely that the sea mammal associates the information that it gathers from tracking with the actual subject. So even if the seal can’t see the target, there’s a high chance the animal already knows what it is before the object enters its peripheral vision.
The Future of Sensor Technology
Humans hold some of the weakest natural sensing abilities in the animal kingdom. Because of this, scientists draw inspiration from other species to create machines that help people better understand their environment. The results of the MIT study contribute to this insatiable need by enhancing the design of tracking pods. Fishermen, for example, could follow a school of fish more accurately, minimizing time spent in congested waters. Divers may also benefit from the technology by using it to avoid aggressive predators during underwater excursions.
“We already have a few sensors that can detect velocity, but now that we know better what they can do, we can use them to track sources of pollution and the like,” explained Michael Triantafyllou of MIT’s Department of Mechanical Engineering. “By having several whiskers on a vehicle, like the seal, you can, for example, detect a faraway plume, and track it all the way to the end.”