I recently did some walkabout lectures at a local middle school. The format was to walk around the campus for about 45 minutes and discourse on the various organisms we encountered. I did this six times with different groups. Aside from the stationary trees and plants, the organisms we encountered most reliably were the little wolf spiders (family lycosidae, most likely genus Padrosa).
Wherever you looked, they ran through the lawns in front of us. They were everywhere. In a cool off-season wandering we encountered hundreds. Starting life about the size of the head of a pin, if they're lucky, they capture enough prey to grow, shed their skins and grow again. Judging from sheer numbers, they must be one of the most successful lifeforms around and each full-sized individual must represent a dozen or so prey captured/killed.

Gauging by their numbers in that one little off season excursion it is not difficult to believe the memes that spiders consume some 500 million tons of insects every year worldwide, or that wherever you go there is a spider within 6 feet of you. But life isn't all beer and Skittles for them. They are not the apex predator in their world, but serve as fodder for a host of other creatures.

One of their adaptations that seems to contribute to their success is maternal care. They do not spin webs to capture food but the females do fashion an egg case to carry around on their abdomens until they hatch. Then they carry the young on their backs for a few weeks until they are ready to strike out on their own.
A walk along my local river bar often reveals members of the family, the “beach wolf spider” (Arctosa littoralis), often sunning themselves on rocks. The females of this species get pretty big, with a leg span as large as a half dollar in some cases. I have never seen this species carrying young or an egg case.