I had to resubmit this photo when I figured out what this was because it is so fascinating. On the back of this mother spider are many baby spiders. The Wolf Spider carries their spiderlings on their back for about a week while they hunt for food. I could not get over how large she was or what was up with her backside but with further inspection of the photo and investigating on the internet I found out there are indeed many, many baby spiders on her back.
Thanks for the comments. I have to say even as much as I love spiders (from afar) when I look at this photo I get the creeps a little as well. I did not really know what I had because it was dark - I just knew she was a very large spider and very quick - so I was doing some serious dancing and maneuvering to avoid her running right over my foot - oh yeah and a little screaming.
"The best and most beautiful things in the world cannot be seen or even touched - they must be felt with the heart." -Hellen Keller
I was about to post something about the possibility of lots of babies upon its back yesterday but I wasn't quite sure because they were so small. Glad you got an ID on this! Fantastic shot too!
Thank so much. If you look closely in the original you can see some of the little black eyes. My eight year old son actually pointed out that they might be babies from a bug book he has - there was a photo of a scorpion carrying babies in the same manner. At first I thought - 'can't be' - but when I pulled it up on the internet it was true - I found one other photo on 'flickr' of a wolf spider with babies.
Wolf Spider