Anup Shah / Eastern Chimpanzee (Pan troglodytes schweinfurthii) seventeen month old infant male, named Shwali, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) seventeen year old male, named Fudge, hooting, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) seventeen year old male, named Fudge, Gombe National Park, Tanzania

Marie Read / Common mergansers (Mergus merganser) family, female swimming with seventeen ducklings, some of which are riding on her back, Lansing, New York, USA, June.

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) male, seventeen years old, Gombe National Park, Tanzania

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) male, seventeen years old, Gombe National Park, Tanzania

Brent Stephenson / Female common eider (Somateria mollissima) with seventeen chics (probably at least two broods of ducklings that have mobbed together) Gudhjem, Bornholm, Denmark. June.

John Abbott / Decim Periodical Cicada (Magicicada septendecim) on white background, New Brunswick, New Jersey, USA, June.

Fiona Rogers / Eastern Chimpanzee (Pan troglodytes schweinfurthii) seventeen year old male, named Zeus, vocalising, Gombe National Park, Tanzania

Doug Wechsler / Periodical Cicada (Magicicada septendecim) recently metamorphosed, Bear Moutain, Orange County, New York, USA, June.

Pete Oxford / Mexican Axolotl (Ambystoma mexicanum) larva on day seventeen of development, native to Mexico, sequence 13/13

ZSSD / Giant Panda (Ailuropoda melanoleuca) portrait of baby Hua Mei at seventeen-and-one-half weeks old, native to Asia