The Woodworms were colored Red, Teal, Blue, Yellow, and Green. (Teal missing in the picture above). Since we were "hunting" for them while they were on a grassy, green surface, the green Toothus Pickiis were harder to find, or camouflaged and therefore were seen last. (an animal would've been full by the time it saw the green woodworm). Because the Toothus Pickiis had 5 subspecies, each with a different color, the one with green "skin" would survive because the genetic mutation that allowed the woodworm to have green skin would, in turn, allow it to survive and reproduce, which carry the hereditary trait onto its offspring and repeat. The (bright) red woodworms were the easiest to spot for me, so when I was "hunting", I picked up those woodworms first. In a real-world scenario, the population of green Toothus Pickiis would increase due to their ability to reproduce, while the red ones would die out, or go extinct.