I have tentatively identified this spider as a Western Spotted Orbweaver (Neoscona Oaxacensis ) also known as a zig-zag spider. It is a pretty spider with a body length of just under one-half inch.
This spider occurs throughout the mid-west and western U.S., Mexico, Central American and parts of South America. Like most spiders, the orbweaver has venom to subdue its prey, but most sources say the venom is not harmful to humans.
The spiders eat insects and anything else that gets caught in its web. It also eats spider silk. You can watch a short video from the Boyce Thompson Arboretum which shows this spider in action:
Spider silk is a protein fiber. Spiders can produce as many as seven different types of silk. Wikipedia has a long and detailed article on spider silk (link). I will summarize.
Spider silk is five times as strong as the same weight of steel and some silk can stretch up to five times its length without breaking.
Types of silk (from Wikipedia):
Major-ampullate (dragline) silk: Used for the web’s outer rim and spokes and also for the lifeline. Can be as strong per unit weight as steel, but much tougher.
Capture-spiral (flagelliform) silk: Used for the capturing lines of the web. Sticky, extremely stretchy and tough. The capture spiral is sticky due to droplets of aggregate (a spider glue) that is placed on the spiral. The elasticity of flagelliform allows for enough time for the aggregate to adhere to the aerial prey flying into the web.
Tubiliform silk: Used for protective egg sacs. Stiffest silk.
Aciniform silk: Used to wrap and secure freshly captured prey. Two to three times as tough as the other silks, including dragline.
Minor-ampullate silk: Used for temporary scaffolding during web construction.
Piriform: Piriform serves as the attachment disk to dragline silk. Piriform is used in attaching spider silks together to construct a stable web.
It seems that spiders are more complicated than one would initially think. Have you seen this spider around your garden?
The Arizona Brown Spider – a reclusive beastie