Paul D Stewart / Aerial view of Grand Prismatic thermal spring in Yellowstone National Park, USA. The bright colours are natural, coming from thermophile bacteria in the water. People can be seen walking on the raised...

Kathryn Jeffs / Southern Type B Killer whale (Orcinus orca) spyhops to see if Crabeater seals (Lobodon carcinophagus) are potential prey, Antarctica. Taken on location for BBC Frozen Planet series, January 2009

Peter Cairns / 2020VISION / Grey seal (Halichoerus grypus) bull with reflections on water of harbour lights, Shetland Isles, Scotland, UK, June 2010. Photographer quote: 'This 'seal on fire' is actually bobbing in a harbour and...

Sergey Gorshkov / Salmon (Salmonidae) eggs falling to lake bottom, Lake Kuril, Kamchatka, Far East Russia, July

Konrad Wothe / European Bee-eater (Merops apiaster) presents prey item to potential mate, Bulgaria

Kim Taylor / Wood Ant (Formica rufa) workers on top of their nest synchronise ejection of formic acid droplets to maximise deterrent effect on potential predator, UK. Commended in the Audubon Society of Greater De...

Andrew Parkinson / Sika deer (Cervus nippon) female stretching her head back to detect the scent of any potential threat. Arne RSPB Reserve, Dorset, UK, October (non-ex)

Markus Varesvuo / Great Grey Owl (Strix nebulosa) swooping down on potential prey, Rovaniemi Finland March

Marie Read / Mountain Bluebird (Sialia currucoides), male hovering to investigate potential nest hole in burned Jeffrey Pine (Pinus jeffreyi), Mono Lake Basin, California, USA, June.

Marie Read / Mountain Bluebird (Sialia currucoides), male hovering to investigate potential nest hole in burned Jeffrey Pine (Pinus jeffreyi), Mono Lake Basin, California, USA, June.

Eric Medard / Common kestrel (Falco tunninculus) hovering above potential prey, France, February

Andy Rouse / Barn owl (Tyto alba) hunting, looking down for potential prey below, UK March

Tony Heald / Lilac-Breasted roller (Coracias caudatus) watching dragonfly go by, potential prey, Etosha National Park, Namibia

John Cancalosi / Lantern Fly / Machaca (Fulgora lampetis) displaying eye-spots, used to startle potential predators. Santa Rosa National park tropical dry forest, Costa Rica.

John Cancalosi / Lantern Fly / Machaca (Fulgora lampetis) displaying eye-spots, used to startle potential predators. Santa Rosa National park tropical dry forest, Costa Rica.

Kathryn Jeffs / Southern Type B Killer whale (Orcinus orca) spyhops to see if Crabeater seals (Lobodon carcinophagus) are potential prey, Antarctica. Taken on location for BBC Frozen Planet series, January 2009

Nick Upton / Sand Martin (Riparia riparia) pair, newly arrived in spring, flitting around sandy sea cliffs looking for a potential nest site near another perched pair. Cornwall, UK, April.

Nick Upton / Sand Martin (Riparia riparia), newly arrived in spring, flitting around sandy sea cliff looking for a potential nest site near others starting to dig burrows. Cornwall, UK, April.

Nick Upton / Sand martin (Riparia riparia), newly arrived in spring, flitting around sandy sea cliff looking for a potential nest site near a perched pair. Cornwall, UK, April.

Nick Upton / Sand Martin (Riparia riparia) pair, newly arrived in spring, flitting around sandy sea cliffs looking for a potential nest site. Cornwall, UK, April.

Nick Upton / Sand Martin (Riparia riparia), newly arrived in spring, flitting around sandy sea cliff looking for a potential nest site near a perched pair. Cornwall, UK, April.

Luiz Claudio Marigo / Female Black-crowned Tityra (Tityra inquisitor) inspecting a hole as a potential nest in Serrinha do Alambari Environmental Protection Area. Rio de Janeiro State, South-eastern Brazil, October.

Tony Heald / Black-faced Impala (Aepyceros melamis petersi) male jumping ("stotting" or "pronking") to demonstrate fitness to potential mates, competitors and predators. Devil's Thorn fl (Tribulus terrestris) in f...

Chien Lee / Moth caterpillar gives the threatening appearance of a snake head, which may help to ward off potential predators, Gunung Mulu National Park, Sarawak, Borneo, Malaysia

Konrad Wothe / European Roller (Coracias garrulus) presents prey item to potential mate, Bulgaria

Konrad Wothe / European Roller (Coracias garrulus) presents prey item to potential mate, Bulgaria

Kim Taylor / Wood Ant (Formica rufa) workers on top of their nest synchronise ejection of formic acid droplets to maximise deterrent effect on potential predator, UK.

Charlie Summers / Cape Golden Cobra (Naja nivea) foraging for potential prey in the cracks and crevices of an Acacia tree, Kgalagadi TB Park of South Africa, May

Tui De Roy / Austral Parakeet (Enicognathus ferrugineus) investigating potential nest cavity in Southern Beech (Nothofagus sp) forest, Ushuaia, Tierra del Fuego, Argentina

Adrian Davies / Green tree frog {Hyla cinerea} camouflaged on leaf beside potential insect prey, Corkscrew Swamp, Florida, USA.

Matthias Breiter / Arctic Tern (Sterna paradisaea) offering fish to potential mate, Hudson Bay, Canada

Andrew Parkinson / Bengal tiger (Panthera tigris tigris) a 24-month sub-adult watching for potential prey, rear view. Bandhavgarh National Park, Madhya Pradesh, India.

Roger Powell / Puffin {Fratercula arctica} bringing nesting material to burrow, whilst two others prospect potential nest, Caithness, Scotland, UK

Albert Lleal / Close up of a male moth's head and highly sensitive antennas which detect the sexual pheromones released by potential mates, Barcelona, Spain

Barry Bland / Sign warning potential swimmers of Alligators, Everglades, Florida, USA

Piotr Naskrecki / Tiger Moth (Dysschema leda) is brightly colored to advertise its distastefulness to potential predators, Costa Rica

ZSSD / Poison Dart Frog displays striking yellow and black warning coloration which alerts potential predators to its toxicity

Peter Scoones / Caribbean trumpetfish (Aulostomus maculatus) shadowing Parrotfish (Scarus vetula) over coral reef, Bonaire, Netherlands Antilles, Caribbean Pisciverous trumpet fish gains advantage by closely shadowi...

Tui De Roy / Buller's Albatross (Thalassarche bulleri) endemic to New Zealand's southern islands, investigating potential nest site on cliff along Olearia forest edge, Mollymawk Bay, Snares Islands, New Zealand

Fred Bavendam / Feather Star (Crinoidea) utilizing a swimming escape response to elude potential predators, Milne Bay, Papua New Guinea

Tui De Roy / Buller's Albatross (Thalassarche bulleri) investigating potential nest site along Olearia forest edge, Mollymawk Bay, Snares Islands, New Zealand

Jeff Rotman / Man floating on inflatable raft - potential shark attack victim. Hawaii, Pacific Model released.

Charlie Summers / Leopard (Panthera pardus) high in a tree so it has a great vantage point for potential prey. It also climbs trees to avoid insects, catch a bit of a breeze and get away from its enemies. Serengeti Nat...

Chien Lee / Moth caterpillar gives the threatening appearance of a snake head, which may help to ward off potential predators, Gunung Mulu National Park, Sarawak, Borneo, Malaysia

Chien Lee / Moth caterpillar gives the threatening appearance of a snake head, which may help to ward off potential predators, Gunung Mulu National Park, Sarawak, Borneo, Malaysia

Nick Garbutt / Ring-tailed lemurs standing alert {Lemur catta} Berenty Reserve, Madagascar