Will Burrard-Lucas / Ethiopian wolf (Canis simensis) stretching as it wakes up, Web Valley, Ethiopia.

George Sanker / North American beaver (Castor canadensis). swimming in late evening light, Acadia National Park, Maine, USA., September.

Jussi Murtosaari / Goldeneye (Bucephala clangula) with chicks swimming behind, Helsinki, Uusimaa, Finland, May.

Chris Gomersall / Short-beaked common dolphin (Delphinus delphis) breaching alongside ship. Hebrides, Scotland. June

Pal Hermansen / Common eider (Somateria mollissima) male diving in current, seen from a bridge, Straumen, Trondelag, Norway, February.

John & Mary-Lou Aitchison / Juvenile European otter (Lutra lutra) sleeping on a rock, wakes up, Scotland, UK, November.

Graham Eaton / Lesser Scaup (Aythya affinis) captive, Martin Mere Wildfowl and Wetlands Trust. Lancashire, UK. December.

Jeff Rotman / Large number of fishing boats fishing for Sockeye salmon (Oncorhynchus nerka) using drift gill nets, and trying to out manoeuvre other boats. Naknek River, Bristol Bay, Alaska, USA, July.

Ernie Janes / View of wake and the Isle of Skye from ferry to North Uist, Outer Hebrides, Scotland, UK, June.

Suzi Eszterhas / Aerial of whale-watching boat, Skjafandi Bay, Iceland, June 2009.

Suzi Eszterhas / Aerial of whale-watching boat, Skjafandi Bay, Iceland, June 2009.

Nick Upton / Ear-tagged adult female Eurasian beaver (Castor fiber) swimming on the River Otter at dusk, part of a release project managed by the Devon Wildlife Trust, Devon, England, UK, August 2015.

Onne van der Wal / Powerboat sailing through the Whitsunday Islands, Queensland, Australia. November 2012.

Onne van der Wal / A luxury yacht cruising off of Hamilton Island, Whitsundays, Queensland, Australia. November 2012.

Onne van der Wal / Aerial view of power boat sailing past Hamilton Island, in the Whitsunday Island group, Queensland, Australia. November 2012.

Onne van der Wal / Wake of boat on coast of Hamilton Island, Whitsunday Islands, Queensland, Australia, November 2012.

Onne van der Wal / Wake of boat on coast of Hamilton Island, part of the Whitsunday Island group, Australia, Queensland, November 2012.

Frederique Olivier / Adelie penguin (Pygoscelis adeliae) diving near ice flow, Antarctica. Small reproduction only.

Orsolya Haarberg / Boat on Vestfjorden, viewed from top of Reinebringen. Moskenes municipality, Lofoten, Nordland, Norway. August 2012

Pal Hermansen / Aerial shot of ice-breaker 'Kapitan Dranitsyn' going through pack ice surrounding Franz Josef Land, Russian Arctic, July 2004.

Richard Du Toit / Spotted-necked Otter (Lutra maculicollis) swimming, Marievale Bird Sanctuary, South Africa, June.

Solvin Zankl / Dinoflagellates (Noctiluca miliaris) which cause glowing wakes of ships, captive.

Merryn Thomas / View over Penarth Marina, Cardiff, Wales, February 2012.

Merryn Thomas / View over Penarth Marina, Cardiff, Wales, February 2012.

Edwin Giesbers / Two Common Coot (Fulica atra) swimming and leaving wakes on water. The Netherlands, July.

Carol Walker / Wild horses / Mustangs, palomino stallion wakes up resting palomino colt, Pryor Mountains, Montana, USA

DAVID TIPLING / The Wakes - home of Gilbert White - Selborne, Hampshire, UK

Neil Aldridge / Leopard (Panthera pardus) female sleeping in fallen tree. The animal wakes up briefly and falls back asleep. Okavango Delta, Botswana.

Neil Aldridge / Leopard (Panthera pardus) female asleep in long grass. The animal wakes up and looks round. Okavango Delta, Botswana.

Harry Collins / Three-toed sloth (Bradypus) asleep and hanging upside down in a tree. Then the animal wakes up. Costa Rica.

Robin Chittenden / Little auk (Alle alle) swimming on water with reflections, Oulton Broad, Suffolk, UK. December.

Joel Sartore / Photo Ark / Two four-week-old Asian leopard cat kittens (Prionailurus bengalensis) falling asleep, one wakes up and stretches, ACCB Cambodia. Captive.

Frederique Olivier / Close-up of a Northern sea otter (Enhydra lutris kenyoni) sleeping, wakes up and rubs head, grooming, Kachemak Bay, Alaska, USA.