# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DcxJt_Bggip
- **Gondola URL:** https://gondola.cc/posts/70003065-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/5d628814a8.jpg
- **Posted:** 2026-09-02T02:24:00.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

That zig-zag has a name, and the name is wrong.

Argiope aurantia, the yellow garden spider, builds a textbook orb web up to 60 cm across, then lays a dense vertical band of bright white silk through the hub and sits on it, head down, all day. Eugene Simon called the structure a stabilimentum in 1895, on the assumption that it braced and stabilised the web. It doesn’t. The band is only loosely attached to the surrounding threads and contributes almost nothing structurally. The name stuck anyway.

What makes it interesting is that it is built from different material to the rest of the web. An orb is a composite of at least four silks, each from its own gland:

- Frame and radials: major ampullate silk, the dragline, stiff and strong, taking the tension
- Capture spiral: flagelliform silk, extensible to several times its resting length so a flying insect is decelerated rather than bounced out
- Adhesive: aggregate glue, laid as hygroscopic droplets that pull water from the air to stay tacky
- The zig-zag: aciniform silk, from spigots on the median and posterior spinnerets, the same silk used to swaddle prey

Orb silk has evolved towards low ultraviolet reflectance, because most flying insects see into the UV and a web that glows is a web that gets avoided. Aciniform silk kept the reflectance. So the decoration is, to an insect, the single most visible thing in an otherwise near-invisible trap.

That contradiction drives every competing hypothesis: prey lure mimicking the UV signature of flowers, a warning band that stops birds from tearing through a web that costs a night’s silk to replace, or disruptive camouflage for a spider whose paired legs form an X aligned with the band. Field results support all of them, in different species, in different seasons.

A structure can outlive the explanation it was named after.

#stemantics #arachnology #biomaterials #spidersilk #naturalhistory

## Stats

- **Views:** 8,605
- **Likes:** 117
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## Tags

biomaterials, arachnology, spidersilk, stemantics, naturalhistory

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