Each Chameleon will grow at a different rate I assume from what I've read. Certain Chameleon's will just be more enticed to eat more, or if you have more than 1 Cham housed together, beat out other chameleons for food. Simple enough, when the Chameleon has kind of out-grown his jacket, so-to-speak, he/she will shed to make room for a new bigger coat. I can guarantee not all 40 of the Cham's will grow at exactly the same rate and they will probably shed at different times, not by much though, hopefully within at least a week or two of each other. I'm sure you'll see some shed together on the same day, maybe even at the same time or at different times during that day but it's safe to say the fattest one first will prevail. hehe.