I first became aware of the stabilimenta in some spider webs when I lived in a house in a rural location in Kentucky and shared my couple acres with a number of Argiope spiders (Saint Andrews Cross spiders) who liked to weave their webs near my house where the lights presumably helped attract their prey at night.
Those particular spiders created a rather simple but still impressive vertical zig-zag line in the center of their webs. From then until now my understanding was that the stabilimenta served to make the web visible to birds and other non-prey (and I was appreciative of their foresight when hiking along wooded trails).
But now I learn from the Wikipedia page that the stabilimenta may serve other purposes, including camouflage, or making the spider appear larger and more fearsome or more sexually attractive, or that it provides a thermoregulation function, or that the stabilimenta reflect ultraviolet light and thus attract insects.
I can't leave the topic without mentioning the most famous stabilimenta of all time:
In 1948 E.B. White wrote an essay for The Atlantic about the death of a favorite pig -
I spent several days and nights in mid-September with an ailing pig and I feel driven to account for this stretch of time, more particularly since the pig died at last, and I lived, and things might easily have gone the other way round and none left to do the accounting. Even now, so close to the event, I cannot recall the hours sharply and am not ready to say whether death came on the third night or the fourth night. This uncertainty afflicts me with a sense of personal deterioration; if I were in decent health I would know how many nights I had sat up with a pig...Some of you will enjoy reading the full essay at the link.
Charlotte's Web image and link to the essay via Ghost of the Talking Cricket. Top photo credit: Muhammed Karim.