The Structure of an Avida Critter

Each cell of the Avida matrix can contain an Avida “critter”, a virtual computer that runs a program. The virtual computer is analogous to the chemical and physical underpinnings of the biological world. The program is the critter’s genome and is what evolves in Avida. Running the program consumes a resource, computer cycles. Additional resources can be defined in some Avida versions.

Image copyright by Robert T. Pennock, used by permission
http://www.msu.edu/~pennock5/research/Avida-ED.html