| − | [[Feather]]s with smooth [[barbule]]s but no hooked barbules.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia Educational Ministries, Inc. 1998</ref> | + | '''Down feathers''' are [[feather]]s with smooth [[barbule]]s but no hooked barbules.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia Educational Ministries, Inc. 1998</ref> |