Ingo Arndt / Eastern grey kangaroo joey looking out of pouch, Wilsons Promontory NP Australia

Ingo Arndt / Eastern grey kangaroo female with joey peering out of pouch {Macropus giganteus}. Wilson Promontory NP Australia

Claudio Contreras / Merriam's kangaroo rat (Dipodomys merriami). El Pinacate Biosphere Reserve, Sonoran Desert, northwest Mexico. July.

Mary McDonald / Bannertailed Kangaroo Rat (Dipodomys spectabilis) in nest hole at night, note full cheek pouches, captive, USA

Barry Mansell / Kangaroo rat (Dipodomy sp) captive

Mary McDonald / Banner-tailed kangaroo rat {Dipodomys spectabilis} outside its den, captive, Southern Arizona, USA.

Mary McDonald / Banner-tailed kangaroo rat {Dipodomys spectabilis} outside its den. captive, Southern Arizona, USA.

Constantinos Petrinos / Weedy Seadragon {Phyllopteryx taeniolatus} Kangeroo Island, Australia

John Cancalosi / Western grey kangaroos {Macropus fuliginosus} young males sparring, South Australia

Michael W. Richards / Skippy 'The bush kangeroo' with handler Ron Roman, Australia. 1997

Michael W. Richards / Skippy 'The bush kangeroo' with handler Ron Roman, Australia 1997

Mary McDonald / Bannertail kangaroo rat {Dipodomys spectabilis}foraging with full cheek pouches, captive, Arizona, USA.