Thanks a lot everybody! To answer some questions:
The snake "standing up" doesn't have yellow belly in it- its just a pretty intense looking super pastel.
Also, the background from these photos was black velvet. I find it helpful to get velvet with the finest fibers possible and to rotate it to an angle where the velvet is absorbing all the light that hits it. This minimizes reflection off of the fibers and keeps everything very uniform and black.
Thanks again!
Aaron