Spiders and webs as ornament, and how an orb web is really built

The spiderweb is one of the most drawn shapes in decoration and one of the least accurately drawn. Nearly every version is a set of concentric rings joined by evenly spaced spokes, hub dead centre, perfectly symmetrical. A real orb web is none of those things, and the ways it differs are the ways it is more interesting. This is how one actually gets built, what the parts are called, and what to look for in a web pattern you are going to live with.

The build order

An orb web is built outside in and then inside out, in a fixed sequence. The spider starts with the bridge line: a thread released into moving air until it snags something across the gap. That one line is the hardest part of the job and everything else hangs off it.

From the bridge the spider lays a frame, usually a rough Y or a polygon of a few heavy threads that defines the outer limit of the web and anchors it to leaves, stems or masonry. Then come the radii, laid one at a time from the frame into the centre, each one walked out and back. The hub is reinforced where they meet.

Only then does the spiral go in, and it goes in twice. First a temporary spiral of plain, non-sticky silk is laid from the hub outwards, widely spaced, as scaffolding to walk on. Then the capture spiral, the sticky one, is laid from the outside back in, much more tightly spaced, and the spider eats the temporary spiral as it passes it. The finished web contains almost none of the silk it was built with.

The parts, and the words for them

The spokes are radii. The sticky rings are the capture spiral, and it is a true spiral, not a stack of rings: one continuous thread working inwards. The centre is the hub, and immediately outside it is the free zone, a gap with no capture spiral at all, which the spider uses to cross from one face of the web to the other.

Radius counts vary by species and by individual. Garden orb weavers commonly run somewhere in the twenties to forties, not the eight or twelve that decoration tends to use. Spacing between turns of the capture spiral is set by the spider's own leg length, which is why web geometry scales with the animal.

Some orb weavers add a stabilimentum, a band or cross of conspicuous white silk across the hub. Its function is argued about, with candidates including making the web visible to birds so they do not fly through it. It is a real structure, and a web with one looks much less like the decorative version than a web without.

The silk

An orb weaver does not make one silk. It has several gland types producing threads with different jobs: a stiff, strong dragline for the frame and radii and for abseiling, a stretchy core thread for the capture spiral, a glue that gets applied to that core in droplets, a wrapping silk for prey, a tougher silk for the egg sac, and a cement for the attachment discs that stick a thread to a wall.

Dragline silk is the famous one. For its weight it is roughly as strong in tension as steel, and it is considerably tougher, meaning it absorbs more energy before failing, because it stretches a long way first. That combination is what stops a web from shattering when a heavy insect hits it at speed.

Not all capture silk is glued. One family of orb weavers uses cribellate silk instead, combed out into a dry woolly mass of fine fibres that snags the hairs and claws on an insect's legs. Those webs look faintly fuzzy rather than beaded, and under a drop of water a glued web shows the beads clearly while a dry one does not.

Four things the drawn web gets wrong

First, concentric rings. A drawn web almost always shows closed circles. A real one shows a single spiral, so if you follow a thread round it does not meet itself, it steps inward.

Second, straight chords. Decoration draws the spiral as straight lines between spokes, which gives that angular look. Real capture spiral sags between radii under its own weight and under the glue, so every segment is a shallow curve.

Third, the hub in the middle. In a vertical web the hub usually sits above centre, because the spider runs downwards faster than upwards and the lower half is therefore the useful half. The web is top-heavy in geometry and bottom-heavy in area.

Fourth, perfect regularity. Real radii are unevenly spaced because the anchor points are wherever the leaves happened to be, and a web two days old has gaps, repairs and a line of wrapped debris down one side.

Choosing a web pattern that holds up

At small sizes the correctness matters less than the spacing, because a web on a pendant is a texture, not a diagram. What ruins a small web is even density: if the gaps between spiral turns are the same at the edge as at the centre, the whole thing goes grey and reads as a disc. The gaps should widen outward. A piece like a web pendant lives or dies on that one decision.

Odd numbers of radii sit better than even ones, for the same reason odd numbers of anything do: an even count produces a straight line through the middle and the eye follows it out of the design. Eight is the number everybody uses and it is the worst, because it also produces two diagonals and a cross.

For a flat round object the web is close to the ideal pattern, which is why it keeps turning up on coasters and plates. Radial symmetry means there is no wrong way up and no edge that needs to be at the front. On a round coaster the practical question is not the geometry at all but whether the open parts of the pattern go all the way through, because an openwork web will let a wet glass mark the surface underneath it.

How webs became ornament

The web entered decoration from two directions at once. One is textile: openwork lace and the finest hand knitting have been described in terms of cobwebs for centuries, and the comparison is technical rather than poetic, because both are a net of fine threads held in tension by a frame. Shetland lace knitting produced shawls fine enough to pull through a ring, and the gossamer weights are still named for it.

The other is emblematic. A cobweb across a doorway has meant neglect and abandonment since long before anybody made one on purpose, and Ovid's story of Arachne, a weaver turned into a spider for the offence of being too good at weaving, gave the animal a permanent association with craft and punishment. That is myth, and it is worth saying so, but it is why the spider reads as a maker rather than only as vermin.

Art Nouveau took the web seriously as a structural motif around the turn of the twentieth century, and Victorian jewellers made spider and web brooches in quantity. A woven or burnt-out web in cloth, such as a lace mantel scarf, belongs to the textile tradition, and the thing to know about living with it is that genuinely open lace catches on everything. Keep it where hands and sleeves do not pass, and store it flat rather than folded on the same creases.

The spider itself is a harder sell as an object than the web, because the shape is mostly legs and legs are what breaks. A cast brass spider solves it the way casting always solves it, with thicker limbs than the animal has, which is also why it survives being handled.

Questions people actually ask

How does a spider build an orb web?

It starts with a bridge line carried on the air, adds a frame and then the radii, then lays a temporary non-sticky spiral outwards as scaffolding, and finally lays the sticky capture spiral inwards, eating the temporary one as it goes.

Is spider silk really stronger than steel?

For its weight, dragline silk is roughly comparable to steel in tensile strength, and it is tougher because it stretches a long way before breaking, so it absorbs much more energy.

Why do spiders rebuild their webs?

The glue on the capture spiral loses its stickiness and the web collects damage and debris. Many orb weavers take down and rebuild the capture spiral regularly, eating and reusing the old silk.