The Four Feather Types (IMAGE) University of Bristol Caption These are the four feather types: filaments, filament bunches, tufted filament, down feather. Scale bars for photos, are a-d: 100μm, 200μm, 500μm and 1mm). Credit Zixiao Yang Usage Restrictions Single use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.