Marie Read / Eared grebes (Podiceps nigricollis), pair, one adult feeding one of two chicks riding on the other adult's back, Bowdoin National Wildlife Refuge, Montana, USA

Marie Read / Eared grebes (Podiceps nigricollis), pair, one adult carrying food (damselfly) for two chicks riding on the other adult's back, Bowdoin National Wildlife Refuge, Montana, USA

Marie Read / Eared grebes (Podiceps nigricollis), pair, one adult feeding chick riding on the other adult's back, Bowdoin National Wildlife Refuge, Montana, USA

David Woodfall / Surfers & pleasure boats ride the bore, seen from the river. Severn Estuary. England

Kristel Richard / The huntsman is surrounded by the hounds at the opening meet of the Quorn Hunt, in Leicestershire, England, UK. October 2009

Kristel Richard / A foxhound walks ahead of the huntsman at the opening meet of the Quorn Hunt, in Leicestershire, England, UK. October 2009

Kristel Richard / A whipper-in, wearing the traditional hunting attire, and the modern foxhounds run at the opening meet of the Quorn Hunt, in Leicestershire, England, UK. October 2009

Andy Sands / Stag Beetle (Lucanus cervus) male on Oak branch with woodland ride, West Sussex, England. UK

Pete Oxford / Chagras or cowboys on an overnight ride at a hacienda during the annual cattle round-up, with Mt Antisana in the background, Ecuador

Pete Oxford / Chagra cowboy portrait with roses in his hat band, on an overnight ride at a hacienda to herd cattle, Andes Mountains, Ecuador

Pete Oxford / Two Chagra cowboys on an overnight ride at a hacienda to herd cattle, Andes Mountains, Ecuador

Alex Mustard / Pair of Emperor shrimp (Zenopontonia rex / Periclimenes imperator) female is the larger one, hitch a ride on a large nudibranch (Tambja luteolineata) and pick food from the seabed with their claws. Bi...