From top left: Harry Taylor/Getty Images, Dmitry Gool/iStockphoto/Thinkstock, Dirk Wiersma/Science Source, Martyn F. Chillmaid/Science Source, Sawayasu Tsuji/iStockphoto, Kae Deezign/Shutterstock, Charles D. Winters/Science Source, Andrew Lambert Photography/Science Source, Charles D. Winters/Science Source