What Major Ecological Roles Exist?
Numerous ecological roles exist. These include microscopic, small, medium, and large-sized herbivores, producers, predators, scavengers, and parasites. There are an estimated 7 million plant and animal species on the planet today, most of them insects, occupying every conceivable niche. The most popular niches appear to be herbivore and parasite, with predators being the smallest niche. However, it also seems that, among all ecological roles, that of predator captures the popular imagination the most. All the major ecological roles have been almost continuously occupied since at least the Cambrian Explosion, a major episode of evolutionary diversification roughly 542 million years ago. Some paleontologists have postulated that the evolution of predation is partially responsible for the evolutionary diversification that occurred during the Cambrian. In any case, by the end of the Cambrian, all major ecological roles were populated, except the largest organisms were only about a meter in
