African rail
These birds probe with their bill in mud or shallow water, also picking up food by sight. They mainly eat insects, crabs and other small aquatic animals.
Detritus
There is an extremely large number of detritus feeders in water. After all, a large quantity of material is carried in by water currents. Even if an organism stays in a fixed position, as long as it has a system for filtering water, it will be able to obtain enough food to get by. Many rooted organisms survive in this way, using developed gills or tentacles to filter the water to take in food, a process known as filter feeding.