As far as I know, there are no studies of the biota that lives under bridges, in the tropics or anywhere else. This is a subject I thought of tackling myself since I was a student biologist. But such a study would require resources that I do not have. Nevertheless, I did this photographic collection of life under and near a bridge in Cascajal, Coronado, central Costa Rica. My family was having some fun there and we found these flowers, arachnids (Opiliones), a freshwater crab and even an abandoned bird's nest.