58.504 Изгледи
Scientists believe that birds evolved from reptiles. Birds have backbones, and they lay eggs, but they’ve developed a unique feature that sets them apart from all other animals – feathers. Feathers are made of the same stuff human fingernails and hair are made from – a protein called keratin. Feathers, combined with lightweight bones, powerful wings and strong hearts let birds fly.
Първа ефирна дата : Sep 10, 1993
Дата на последния ефир : Jun 20, 1998
Епизод : 100 Епизод
Сезон : 5 Сезон
Времетраене: 26 минути
Студио: PBS
Страна: United States of America
