Animal Senses #8: Surface Vibrations
Surface vibrations. Vibrations that travel along the surface (obviously). Some question how they are different from sound – aren’t both vibrations? Yes, they do have their similarities. But there are also differences, which is why Ed Yong dedicates a chapter to surface vibrations in Immense World , albeit a small one. The first difference is that sound vibrations are in the same direction in which sound travels; whereas surface vibrations are perpendicular to the direction that the vibration travels. The bigger difference is that, until recently, scientists focussed only on sound but not surface vibrations, so they didn’t know much of how surface vibrations are used by different creatures. Take the spider web. We think of it as a trap. Yes, it is that, but it is also a “surveillance system”, extending the spider’s senses well beyond its body. The spider can sense vibrations in the web. They can differentiate the vibrations caused by rustling wind from a leaf that fell to a str