on arrangement of the spider families:
The families are arranged in this way purely out of convenience.
Three points should be noted.
Families grouped together are not necessarily related to one
The arrangement is not intended to reflect any evolutionary
scale, although spiders with two pairs of book-lungs (e.g.,
Theraphosidae) are regarded as being more primitive than most
The grouping is oversimplified. For instance, free-roaming spiders
grouped under "hunters" may spin a web (e.g., certain
Wolf Spiders and Nursery Web Spiders, as well as a few Jumping
Spiders). Certain spiders under the category of "orb-web
builders" do not build an orb-web, and certain spiders
outside this category (e.g., Uloboridae) do build an orb-web.
However, the categorisation holds good in most instances.