An Immense World: How Animal Senses Reveal the Hidden Realms Around Us

by Ed Yong

An orb-weaver not only builds its own vibrational landscape but also can adjust it as if tuning a musical instrument. The range of that instrument is immense. By using gas guns to fire projectiles at individual silk fibers and analyzing the threads with high-speed cameras and lasers, Mortimer concluded that some silks can transmit vibrations over a wider range of speeds than any known material. A spider can theoretically change the speed and strength of those vibrations by altering the stiffness of its silk, the tension in the strands, and the overall shape of the web. It can do this every time it builds a new web, by pulling silk out of its body at different speeds, by creating fibers of different thicknesses, or by adding tension to the new strands. It can adjust webs that have already been spun by adding, removing, or tugging on specific threads. It can rely on silk’s natural tendency to contract in humidity, and then stretch out these tightened threads to just the right degree. It’s not clear when orb-weavers might decide to do any of this, but they certainly have the option of tuning their own senses and defining their own Umwelt according to their needs. Zoologist Takeshi Watanabe showed that the Japanese orb-weaver Oclonoba sybotides changes the structure of its web when it is hungry. It adds spiral decorations that increase the tension along the spokes, improving the web’s ability to transmit the weaker vibrations transmitted by smaller prey. When it is famished, e...