In The Middle Of Nowhere

From the pavement running along the front gardens of a row of neat town houses, I can see a spider, about 3 cm big, seemingly hanging in mid-air.

A single thread is its bridge, leading from one big rhododendron bush to another. Below and above the spider, there is nothing but air.

And it sits there, or, rather, is suspended there, waiting for any uncautious flying insect coming its way.

Does the spider know or feel or sense where it is? Can it somehow measure the distance necessary from one point in its relatively small universe to the next, in order for it to have a chance for a meal? How and when did it decide to fasten its thread right there, between these two shrubs, and not between the next two, or between the platane trees along the pavement?
Isn't it worried about being so clearly visible to birds, who'd surely appreciate a juicy snack with eight legs?

Life without a frontal cortex must be so much easier.

Yes, there is such a thing as thinking too much (Jonah Lehrer makes that point quite understandable even for the likes of me in "How we decide"). Although that happens to me only very rarely.