Insect and Spider Identification: CLOSED: Green spider with changing eye color, 1 by sybrandy

sybrandy wrote:
I´m writing from Florianópolis, southern Atlantic coastal florest – Brazil.
Attached you´ll find a photo-set of a green spider, around 2 cm big
Photos have been taken with Canon A610 – point-and-shoot, marco and afterwards cutout with Picasa, taken in a 1 second burst, no flash.
I was amazed seeing the change of color of the eyes in less than a second (sequence: highleft highright, bottomleft, bottomright). Just look! Could somebody tell me which spider we´re talking about and explain me the how and why this makes sense! Thanks a lot.