Daniel Nunez / Yellow-blotched palm-pit viper (Bothriechis aurifer) resting on branch in cloudforest at night, Ranchitos del Quetzal Reserve, Baja Verapaz, Guatemala.

Carol Walker / A wild sorrel stallion looking back on snow-covered landscape, Green Mountain, Wyoming, USA. January.

Carol Walker / A wild grey pinto stallion trotting over grassland, Green Mountain, Wyoming, USA. May.

Andy Sands / Slime mould (Stemonitis sp.) newly emerged bright yellow sporangia on rotting log, Buckinghamshire, England, UK. September. Focus stacked.

Andy Rouse / Sparkling violetear hummingbird (Colibri coruscans) perched on branch, reaching up to catch a bee, Cloud forest, Ecuador.

Alex Mustard / Looking down at the top of a submerged reef covered in corals (Acropora spp. and Pocillopora sp.), Fathers Reef, Lolobau Island, Papua New Guinea. Bismark Sea, Pacific Ocean.

Alex Mustard / Marine iguana (Amblyrhynchus cristatus) feeding on green algae on seabed, with more iguanas on the surface behind, Cape Douglas, Fernandina Island, Galapagos Islands, Pacific Ocean.

David Perpinan / Flathead grey mullet (Mugil cephalus) and Salema (Sarpa salpa) school swimming past the camera in the mouth of the Besos river. The fish enter and leave frame. Barcelona, Spain. October.

David Perpinan / Catalan chubs (Squalius laietanus) swimming around, showing interest in the camera. The fish enter and leave frame. Besos river, Barcelona, Spain. October.

David Perpinan / Catalan chubs (Squalius laietanus) enter frame, swim around and then leave frame. Besos river, Barcelona, Spain. October.

David Perpinan / Flathead grey mullet (Mugil cephalus) and Salema (Sarpa salpa) school swimming past camera in the mouth of the Besos river. The fish enter and leave frame. Barcelona, Spain. October.

David Perpinan / Common carps (Cyprinus carpio) enter frame, swim past the camera and then leave frame, Besos river, Barcelona, Spain. July.