Ingo Arndt / Red-eyed tree frog (Agalychnis callidryas) eye closed with semi-transparent eyelid that allows it to see its surroundings even while resting, Costa Rica.

Ingo Arndt / Red-eyed Tree Frog (Agalychnis callidryas) close- up of eye half open, the golden webbed semi-transparent eyelid allows to see its surrounding even while resting, Costa Rica.

Ingo Arndt / Close up of foot and eye of Red eyed tree frog {Agalychnis callidryas}

Nick Garbutt / Female Red-eyed Tree Frog (Agalychnis callidryas) - Caribbean slope race (blue flanks) - obscured in rainforest foliage. Mid-altitude rainforest near Aranal, central Costa Rica.

SCOTLAND: The Big Picture / Red squirrel (Sciurus vulgaris) climbing tree trunk with autumn leaves, Highlands, Scotland, October 2015.

Alex Hyde / Lemur leaf frog (Agalychnis lemur) Central Caribbean foothills, Costa Rica. IUCN Red List critically endangered species.

Alex Mustard / Whitetip shark (Carcharhinus longimanus) head on beneath the surface. Rocky Island, Egypt. Red Sea

David Pattyn / Zanzibar red colobus monkey (Procolobus kirkii) crossing the main road through the Reserve, Jozani forest, Jozani Chwaka Bay NP, Zanzibar, Tanzania, August.

Benjamin Barthelemy / Close-up of a Red fox (Vulpes vulpes) resting, with mountains in the background, Vanoise National Park, Rhone Alpes, France, October.

Ben Hall / Red fox (Vulpes vulpes) peering from behind tree with bluebells in foreground, Cheshire, June.

MYN / JP Lawrence / Strawberry poison frog (Oophaga pumilio) Escudo de Veraguas, Panama. Meetyourneighbours.net project

Georgette Douwma / Big-eye fish (Priacanthus hamrur). Egypt, Red Sea.