Gill filaments are thin, thread-like structures found in the gills of aquatic animals, such as fish. They play a crucial role in the process of respiration by facilitating the exchange of gases. As water flows over the gill filaments, oxygen is absorbed into the bloodstream, while carbon dioxide is released. Each gill filament is covered in tiny, flat surfaces called lamellae, which increase the surface area for gas exchange. This adaptation allows fish to efficiently extract oxygen from water, enabling them to thrive in their aquatic environments.