Crabs breathe for the planet by tilling the mud

A carpet of Ucides cordatus crabs scuttling across a Brazilian mudflat looks like chaotic movement, but it is actually a massive engineering project. These crabs dig intricate burrows that reach over a meter deep, acting as a natural drainage and ventilation system for the coastline. By tunneling through the heavy, waterlogged mud, they allow oxygen to penetrate deep into the earth. This process, known as bioturbation, prevents the soil from becoming a stagnant trap and fundamentally changes how the ecosystem handles greenhouse gases.