Pretty sure this is an Arctosa littoralis, because it appears to have what Kevin Pfeiffer referred to on another set of Maryland photos: "Dondale & Redner's (1983) key gives the following characteristics for littoralis: "Femur I with two prolateral macrosetae near tip . Tibia III with three retrolateral macrosetae. Legs usually with dark rings." "

Arctosa littoralis has been identified by bugguide on this same beach, located on the Western Shore of the Chesapeake Bay before. Each time, I have marveled at the spider because the colors seem to match the surroundings. Can it change its colors like chameleons or cuttlefish, do the colors change based on the physics related to light, a combination or something else? I don't know the answer.

I am going to post several photos of this spider taken over the course of 8 minutes that show how the spider seemed to change its colors.

Photo 1 - 6:22PM The spider is in a shaded area and appears darker. Note that if you look closely the pattern on its abdomen appears to have a face with eyes looking at you.
Photo 2 - 6:22PM Close up of the spider's abdomen with what appears to be a fake face.
Photo 3 - 6:28-6:29PM The spider decides to move somewhere without human paparazzi. In the late day sunshine, the abdomen looks completely different. No face, seemingly different pattern. It has now become a bland sand color
Photo 4 - 6:30PM The spider decides to climb a large piece of driftwood. The coloration seems to shift to match, the tips of the legs are darker, the patterns more bold but perhaps slightly different.
Photo 5 - 6:32PM The spider realizes the human paparazzi is still following it and moves on to a location on the beach with wetter, and darker driftwood and lots of multicolored beach pebbles. It now seems to have a pink-orange patch that matches some of the beach pebbles.

As I am not an expert so please forgive me if these observations are obvious to experts. If that is the case, please direct me to literature which I will read.