Marie Read / Common loon (Gavia immer) adult swimming with a chick resting on its back, Presque Isle County, Michigan, USA, June.
Bruce Thomson / Spinifex pigeon (Geophaps plumifera) flock on stony desert floor, Diamantina River, Queensland, Australia.
Tui De Roy / Marine iguana (Amblyrhynchus cristatus) basking on driftwood, Fernandina Island, Galapagos, South America.
Uri Golman / Close up of a silverback Mountain gorilla (Gorilla beringei beringei) face with eyes closed, and hand / fingers, Virunga National Park, Democratic Republic of Congo.
David Pattyn / Great crested grebe (Podiceps cristatus) parent bird trying to rest with one of its young that keeps begging for food. Valkenhorst Nature Reserve, Valkenswaard, The Netherlands. June
Carlos Zorrilla / Common potoo (Nyctibious griseus) sleeping as chick yawns next to it, Ecuador, March.
Richard Du Toit / Yellow mongoose (Cynictis penicillata) resting, Kgalagadi Transfrontier Park, Northern Cape Province, South Africa.
Mark MacEwen / Southern elephant seal (Mirounga leonina), two females sleeping. St Andrews Bay, South Georgia. October.
Alex Mustard / School of Oriental sweetlips (Plectorhinchus vittatus) gather tightly together as they rest during the day, with a Clown triggerfish (Balistoides conspicillum) and Midnight snappers (Macolor macularis...
Oliver Wright / Marbled white butterfly (Melanargia galathea) photographed in early morning light. Ledston, Yorkshire, June. Focus stacked image.
Oliver Wright / Portrait of a Emerald damselfly (Lestes sponsa) Yorkshire, August. Focus stacked image.
Oliver Wright / Portrait of a Common darter (Sympetrum striolatum) Yorkshire, July. Focus stacked image.
Danny Green / Mountain hare (Lepus timidus) resting Cairngorms, Scotland, March
Alex Mustard / RF - Pod of Spinner dolphins (Stenella longirostris) cruise in formation over the sand of a lagoon while sleeping. Egypt. Red Sea (This image may be licensed either as rights managed or royalty free.)
Erlend Haarberg / Red fox (Vulpes vulpes), on spring snow, Vauldalen, Norway, April.
Danny Green / Ringed seal (Pusa hispida) resting on ice, reflected in water. Svalbard, Norway. July.
Danny Green / Reindeer (Rangifer tarandus) hunkering down in snow during blizzard. Svalbard, Norway, April.
Danny Green / Polar bear (Ursus maritimus) sleeping in snow. Churchill, Manitoba, Canada, November.
Danny Green / Polar bear (Ursus maritimus) female resting with cubs on glacier. Svalbard, Norway, July.
Danny Green / Polar bear (Ursus maritimus) and cubs resting on sea ice. Svalbard, Norway, July.
Danny Green / Polar bear (Ursus maritimus) resting in snow. Svalbard, Norway, July.
Alex Mustard / Green turtle (Chelonia mydas) resting on sea floor and two juvenile Golden trevally (Gnathanodon speciosus). Marsa El Shouna, Marsa Alam, Egypt.
Neil Anderson / Red squirrel (Sciurus vulgaris), two curled up asleep in drey inside nest box. Nest of lichen and Pine needles. Highlands, Scotland, UK. Medium repro only.
Clay Bolt / Blue-banded bee (Amegilla sp) males sleeping on stem. Halmahera, North Maluku, Indonesia.
Fred Olivier / Close-up of a Northern sea otter (Enhydra lutris kenyoni) sleeping, with paws over eyes, Kachemak Bay, Alaska, USA.
Bernard Castelein / Coquerel's sifaka (Propithecus coquereli) in tree, relaxing, Ankarafantsika National Park, Madagascar
Alex Mustard / Common seahorse (Hippocampus kuda) female wrapping her prehensile tail around piece of wood on the seabed. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.
John Chan / Anna's Hummingbird (Calypte anna) chick, sleeping in nest, Southern California, USA, March.