Subject: I am looking for an organism for an art piece

Hello, I am looking for some help on the following problem.  I will be creating an art piece to be shown 
in a public space in a downtown city.  I do have a background in electronics and fine art, and I am 
looking for an organism that I can control with use of light, sound, etc. for the following purpose.  I am 
trying to create a piece that will monitor the foot traffic outside the front of a storefront.  The foot 
traffic will feed into a microcontroller that will then effect the organism.  The main idea is that after the 
month-long installation, the viewer will be presented with a living graph of downtown motion.  If you 
have any ideas I would greatly appriciate it.  I don't really have a strong background in biology, so I 
appriciate all help I can get.  Thank You

Re: I am looking for an organism for an art piece