symbioses

Cephalotes grandinosus, an herbivorous ant Why are there so many ants? This is a more perplexing question than it may seem.  At first glance ants are predators and scavengers.  Yet predators should be few in number, balanced on a narrow trophic peak and depending on high prey biomass to exist.  Why are terrestrial ecosystems dominated by these little hunters? A landmark study several years ago by Dinah Davidson provided an answer:  many ants are not predators at all.  They're herbivores.  Sure, they snack now and again on flesh.  But ants get most of their energy from plants, either…