Scientific investigations sometimes take unexpected twists and turns. When Emma Harrison, a graduate student at the University of Pennsylvania, began digging trenches in the mountains of Puerto Rico to study how the soil mantle responds to rapid changes in erosion, she couldn’t help but notice the worms.
The thick Puerto Rican soils were chock-full of the wriggling creatures: endogenic worms, which spend their lives burrowing through the soil and feeding on bits of decaying organic matter underground, as well as much larger anecic worms, which in the Luquillos are typically 2 millimeters wide and as long as a human forearm. Anecic earthworms live deeper in the soil profile but build long, vertical burrows so they can feed on organic litter at the surface.