Some of them are orb weaving spiders and some of them are non orb weaving spiders.

Nick Sears demos the Orb

When you look at this orb web, you're actually seeing many types of silk fibers.

There's the aggregate and flagelliform silk glands which combine to make the sticky capture spiral of an orb web.

This is the silk that's used to make the frame and radii of an orb web, and also the safety trailing dragline.

It's been hypothesized that orb weaving spiders, like this argiope here, should have the toughest dragline silks because they must intercept flying prey.

In fact, the toughest dragline in this survey is this one right here in this white region, a non orb web weaving spider.

And He it is Who hath created the night and the day, and the sun and the moon, each in an orb floating.

And He it is Who hath created the night and the day, and the sun and the moon, each in an orb floating.

The 21 species are indicated here by this phylogeny, this evolutionary tree, that shows their genetic relationships, and I've colored in yellow the orb web weaving spiders.

Inventor Nick Sears demos the first generation of the Orb, a rotating persistence of vision display that creates glowing 3D images. A short, cool tale of invention.

So if you ever have the opportunity to dissect an orb web weaving spider, and I hope you do, what you would find is a bounty of beautiful, translucent silk glands.

In an orb web weaving spider, you can find seven types of silk glands, and what I have depicted here in this picture, let's start at the one o'clock position, there's tubuliform silk glands, which are used to make the outer silk of an egg sac.