Milan Radisics / Tracking aerial shot of the source of the Rio Tinto river, the river is coloured by minerals leeching from the surrounding terrain, Andalusia, Spain, January 2019.

Ingo Arndt / Close up of frozen lake in winter, Germany

Alex Hyde / Peacock butterfly (Inachis io) feeding on Goat Willow catkins (Salix caprea), an important food source for pollinators in early spring. Peak District National Park, UK. April.

Hougaard Malan / Rock formations on Anse Source d'Argent beach. La Digue Island, Seychelles. November, 2012.

Hougaard Malan / Rock formation on Anse Source d'Argent beach. La Digue Island, Seychelles. November, 2012.

Hougaard Malan / Rock formations in clear water on Anse Source d'Argent beach. La Digue Island, Seychelles. October, 2012.

Ammonite / Honey bee (Apis mellifera) performing a waggle dance inside a hive to indicate the position and quality of a food source to other workers, France, July.

Ammonite / Close-up of Honey bee (Apis mellifera) performing a waggle dance on the edge of a swarm, indicating the position and quality of a food source, France, May.

Ammonite / Close-up of Honey bee (Apis mellifera) performing a waggle dance on the edge of a swarm, indicating the position and quality of a food source, France, May.

Ammonite / Close-up of Honey bees (Apis mellifera) performing a waggle dance on the edge of a swarm, indicating the position and quality of a food source, France, April.

Alex Mustard / Emperor shrimp (Periclimenes imperator / Zenopontonia rex) hitchhiking on large t-bar nudibranch (Ceratosoma trilobatum) The shrimp gains food source and protection on the toxic seaslug. Bitung, North...

Alex Mustard,Alex Mustard / A blue light fluorescence photo of Jewel anemones (Corynactis viridis). The blue light source excites the fluorescent pigments in the anemones, which emit light of other colours. The muddy seabed and...

Igor Shpilenok,Igor Shpilenok / Kamchatka Brown Bear (Ursus arctos beringianus) stands on its back legs to more easily determine the source of an unfamiliar sound. Kronotsky Zapovednik Nature Reserve, Kamchatka Peninsula, Russian Fa...

David Noton / Dramatic evening sky over Anse Source d'Argent, La Digue. Seychelles. February 2007.

Terry Whittaker / 2020VISION / Feral pigeon (Columba livia) on ground, with people's feet in the background, South Bank, London, England, UK, September. Did you know? In the 16th Century England pigeon guano was the only source of...

Alex Mustard / 2020VISION / Thong seaweed (Himanthalia elongata) and various other seaweeds in shallow water, Cairns of Coll, Island of Coll, Inner Hebrides, Scotland, UK, North Atlantic Ocean, August. Did you know? Seaweed is a...

Simon Colmer / Honey bee (Apis mellifera) returning to hive and communicating nectar source to other workers, Sussex, UK

Juergen Freund / Moromaho Island is home to thousands of Coconut palms (Cocos nucifera). Twice a year farmers come to this island to harvest copra, the meat of the coconut, which is the source of coconut oil. Wakatobi...

Tim Laman / Large school of Trevally (Caranx) shelter beneath the jetty at Arborek Village. Many village docks in this area act as shelter for these fish, which provide a handy source of protein for villagers in...

Michel Roggo / Karst spring where water bubbles up from subterranean source, Julian Alps, Slovenia, June 2008

Solvin Zankl / Fog over the sand dunes of the Namib desert, Namibia - an important source of water for the desert animals.

Hanne & Jens Eriksen / Arabian waxbill {Estrilda rufibarba} flock on food source, Wadi Sardud, Tihama, Yemen

Kim Taylor / Honey bee {Apis mellifera} worker with full pollen sacs executing 'waggle dance' to indicate food source, UK

Pete Oxford / Granite outcrop, Source d'argent beach, La Digue, Seychelles. Coastal landscape

Gavin Hellier / Anse Source d'Argent Beach, La Digue Island, Seychelles, Indian Ocean

Gavin Hellier / Granite Boulder at Anse Source d'Argent beach, La Digue Island, Seychelles, Indian Ocean

Gavin Hellier / Anse Source d'Argent Beach, La Digue Island, Seychelles, Indian Ocean

Gavin Hellier / Anse source d'Argent Beach, La Digue Island, Seychelles, Indian Ocean

Gavin Hellier / Anse Source d'Argent Beach, La Digue Island Seychelles, Indian Ocean

Gavin Hellier / Anse Source d'Argent Beach with granite boulders, La Digue Island Seychelles, Indian Ocean

Gavin Hellier / Anse Source d'Argent Beach with granite boulders, La Digue Island, Seychelles, Indian Ocean

Heather Angel / Chilean monkey flower (Mimulus naiandinus). The lower lip has a groove to guide the pollinator's proboscis to the nectar source, with red spots acting as nectar guides. Cultivated in garden, Surre...

Heather Angel / Lisbon false sun-rose / Yellow rock rose (Halimium lasianthum) flowers. Blotch at base of petals guides pollinators to nectar source.

Olga Kamenskaya / Aerial view near the source of the Lena River. Siberia, Russia. August 2018.

Olga Kamenskaya / Aerial view o near the source of the Lena River. Siberia, Russia. August 2018.

Juergen Freund / Discarded rubber tyre in the sandy shallows. Plastic from tyres are major source of ocean pollution, Sulawesi, Indonesia. November 2018.

Staffan Widstrand / Wild Wonders of China / Dry cattle dung, collected in a plastic bucket by Mongolian herdsmen, to use as fuel, Inner Mongolia, China. This is the main source of heat during the winter in these open grassland steppes.

Ashley Cooper / The Norfolk Naturalists Trust visitor centre at Cley, on the North Norfolk Coast. This is a 'green building' which has a green roof, which collects rainwater for flushing the buildings toilets, a grou...

Ashley Cooper / Visitor centre at Cley Nature Reserve on the North Norfolk coast. This is a green building with a green roof, grey water harvesting, a wind turbine, solar thermal water heating and a ground source hea...

Ashley Cooper / Baling up brashings (dead branches) after timber harvesting on Longridge Fell, Clitheroe, Lancashire, UK, November 2007. The waste wood that would formally have been left to rot is now taken off to a...

Ashley Cooper / Solar thermal and solar PV panels on the roof of the Crystal building which is the first building in the world to be awarded an outstanding BREEAM (BRE Environmental Assessment Method) rating and a LE...

Ashley Cooper / Solar thermal and solar PV panels on the roof of the Crystal building which is the first building in the world to be awarded an outstanding BREEAM (BRE Environmental Assessment Method) rating and a LE...

Ashley Cooper / Visitor centre at Cley Nature Reserve on the North Norfolk coast, An environmentally friendly building with a green roof, grey water harvesting, a wind turbine, solar thermal water heating and a groun...

Ashley Cooper / Visitor centre at Cley Nature Reserve on the North Norfolk coast, An environmentally friendly building with a green roof, grey water harvesting, a wind turbine, solar thermal water heating and a groun...

Ashley Cooper / Solar thermal and solar PV panels on the roof of the Crystal building which is the first building in the world to be awarded an outstanding BREEAM (BRE Environmental Assessment Method) rating and a LE...

Graham Eaton / A PDC (polycrystalline diamond compact) type oil field drill bit on one othe Kimmeridge ledges. Kimmeridge Bay, Dorset, UK, March. The ledges are hard Jurassic age, carbonate rich horizons of Limetone...

Graham Eaton / Glacier on the slopes of the Breithorn, viewed from the Gornergrat observatory, Zermatt, Switzerland, September

Jen Guyton / White-backed vultures (Gyps africanus) pick at the drying and deflated skin of an elephant carcass (Loxodonta africana) while spotted hyenas (Crocuta crocuta) look on, Laikipia Plateau, Kenya. The hye...

Jen Guyton / Rüppell's griffon vultures (Gyps rueppelli) and white-backed vultures (Gyps africanus) feed on an elephant carcass (Loxodonta africana), Laikipia Plateau, Kenya. The elephant was killed by government...

Jen Guyton / White-backed vultures (Gyps africanus) pick at an elephant carcass (Loxodonta africana) while a spotted hyena (Crocuta crocuta) looks on, Laikipia Plateau, Kenya. The hyena is tinted a reddish-brown f...

Jen Guyton / Spotted hyenas (Crocuta crocuta), Rüppell's griffon vultures (Gyps rueppelli) and white-backed vultures (Gyps africanus) at the carcass of an elephant (Loxodonta africana), as the night and day shifts...

Jen Guyton / Rüppell's griffon vulture (Gyps rueppelli) and spotted hyenas (Crocuta crocuta) pick at an elephant (Loxodonta africana) carcass at dawn, Laikipia Plateau, Kenya. This elephant was killed by governme...

Jen Guyton / A spotted hyena (Crocuta crocuta) chases a flock of white-backed vultures (Gyps africanus) away from an elephant carcass (Loxodonta africana), Laikipia Plateau, Kenya. The hyenas are tinted a reddish...

Jen Guyton / White-backed vultures (Gyps africanus) and spotted hyenas (Crocuta crocuta) pick at the drying and deflated skin of an elephant carcass (Loxodonta africana), Laikipia Plateau, Kenya. The hyenas are ti...

David Fleetham / Green turtle (Chelonia mydas) with fibropapilloma tumors covering its head and eyes. Soon the tumors will grow to cover both eyes and limit the turtles ability to locate a food source. Hawaii.

David Fleetham / Green turtle (Chelonia mydas) with fibropapilloma tumors covering its head and eyes. Soon the tumors will grow to cover both eyes and limit the turtles ability to locate a food source. Hawaii.

Matthew Maran / Goat willow (Salix caprea) felled by a Eurasian beaver (Castor fiber) with teeth marks The riverside tree will resprout with new shoots supplying a source of food for the beavers for years to come. De...

Matthew Maran / Goat willow (Salix caprea) felled by a Eurasian beaver (Castor fiber). The riverside tree will resprout with new shoots supplying a source of food for the beavers for years to come. Devon, England, UK...

Matthew Maran / Winter field with stubble and weeds, East Devon, England, UK, November. Fields like this support farmland birds in winter providing a source of seed.

Matthew Maran / Winter field with stubble and weeds, East Devon, England, UK, November. Fields like this support farmland birds in winter providing a source of seed.

Matthew Maran / Winter field with stubble and weeds, East Devon, England, UK, November. Fields like this support farmland birds in winter providing a source of seed.

Matthew Maran / Colaton Brook, a tributary of the River Otter, close to its source on the east Devon Pebblebed Heaths, Devon, England, UK, February.

Jen Guyton / Nile crocodile (Crocodylus niloticus) at water's edge with Great white pelican (Pelecanus onocrotalus) prey, and other crocodiles nearby trying to steal the prey. Msicadzi River, Gorongosa National Pa...

Jen Guyton / Nile crocodile (Crocodylus niloticus) at water's edge to feed on Great white pelican (Pelecanus onocrotalus) prey. With birds on the shore including pink-backed pelicans (Pelecanus rufescens), marabou...

Jen Guyton / Nile crocodile (Crocodylus niloticus) with Great white pelican (Pelecanus onocrotalus) prey. Other birds watch from the shore, including great egrets (Ardea alba), grey herons (Ardea cinerea) and hame...

Jen Guyton / Nile crocodile (Crocodylus niloticus) catching a Great white pelican (Pelecanus onocrotalus) prey, Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sources dry up...

Jen Guyton / Nile crocodiles (Crocodylus niloticus) fighting over Great white pelican (Pelecanus onocrotalus) in the Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sources...

Jen Guyton / Nile crocodile (Crocodylus niloticus) eating Great white pelican (Pelecanus onocrotalus). With birds on the shore including pink-backed pelicans (Pelecanus rufescens), marabou storks (Leptoptilos crum...

Jen Guyton / Nile crocodile (Crocodylus niloticus) underwater holding a Great white pelican (Pelecanus onocrotalus) prey. after a group of the birds dove into the river to hunt fish. Here, the crocodile slowly sw...

Jen Guyton / Nile crocodile (Crocodylus niloticus) with Great white pelican (Pelecanus onocrotalus) prey. Other pelicans flying or wings held up in alarm. Msicadzi River, Gorongosa National Park, Mozambique. Duri...

Jen Guyton / Nile crocodile (Crocodylus niloticus) with Great white pelican (Pelecanus onocrotalus) prey. Other pelicans with wings held up in alarm. Msicadzi River, Gorongosa National Park, Mozambique. During th...

Jen Guyton / Great white pelicans (Pelecanus onocrotalus) and pink-backed pelicans (Pelecanus rufescens) diving into the Musicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sour...

Jen Guyton / Yellow-billed stork (Mycteria ibis) fishing in the Msicadzi River, Gorongosa National Park, Mozambique, while a Nile crocodile (Crocodylus niloticus) swims past. During the dry season many water sour...

Jen Guyton / Marabou stork (Leptoptilos crumenifer) drinking at sunset in the Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sources dry up trapping fish in smaller areas. M...

Jen Guyton / Marabou storks (Leptoptilos crumenifer) and Yellow-billed storks (Mycteris ibis) sweeping the water for fish in the Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many wa...

Jen Guyton / Great white pelican (Pelecanus onocrotalus) preening itself beside the Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sources dry up trapping fish in smaller ar...

Jen Guyton / Great white pelicans (Pelecanus onocrotalus) preening beside the Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sources dry up trapping fish in smaller areas....

Jen Guyton / Nile crocodile (Crocodylus niloticus) emerging from the Msicadzi River, to swallow a mouthful of fish as a yellow-billed stork (Mycteria ibis) scans for fish nearby. Msicadzi River, Gorongosa Nation...

Jen Guyton / Marabou stork (Leptoptilos crumenifer) watching Nile crocodile (Crocodylus niloticus) that has come up to swallow a mouthful of fish. Msicadzi River, Gorongosa National Park, Mozambique. The bird is...

Jen Guyton / Nile crocodile (Crocodylus niloticus) surfacing to eat tiny fish whilst a Marabou stork (Leptoptilos crumenifer) looks on, ready to steal a fish if the opportunity arose. Msicadzi River, Gorongosa Nat...

Jen Guyton / Nile crocodile (Crocodylus niloticus) surfacing to eat tiny fish whilst a Marabou stork (Leptoptilos crumenifer) looks on, ready to steal a fish if the opportunity arose. Msicadzi River, Gorongosa Nat...

Jen Guyton / Nile crocodile (Crocodylus niloticus) surfacing to eat tiny fish whilst a Marabou stork (Leptoptilos crumenifer) looks on, ready to steal a fish if the opportunity arose. Msicadzi River, Gorongosa Nat...

Jen Guyton / Yellow-billed stork (Mycteria ibis) hunting for fish near a Nile crocodile (Crocodylus niloticus) that has come up to swallow a mouthful of fish. Msicadzi River, Gorongosa National Park, Mozambique. D...

Jen Guyton / Birds squabbling over fish in the Msicadzi River. Pink-backed pelican (Pelecanus rufescens) biting at the head of another pelican with a pouch full of fish while a marabou stork (Leptoptilos crumenife...

Jen Guyton / Nile crocodile (Crocodylus niloticus) surfacing to eat tiny fish whilst a Marabou stork (Leptoptilos crumenifer) looks on, ready to steal a fish if the opportunity arose. Msicadzi River, Gorongosa Nat...

Jen Guyton / A Nile crocodile (Crocodylus niloticus) feeding on great white pelican (Pelecanus onocrotalus) in the Msicadzi River, Gorongosa National Park, Mozambique. During the dry season many water sources dry...

Nick Upton / Hoopoe (Upupa epops), drinking from a rare water source, a small stream in the largely parched southwest part of the island, Fuerteventura, Canary Islands, May.

Adrian Davies / Blue Spikemoss (Selaginella uncinata) showing iridescence through change of angle in relation to light source

Adrian Davies / Blue Morpho butterfly (Morpho peleides showing iridescence with change of angle in relation to light source

Doug Perrine / Phyllosoma larva of Spiny lobster (Palinurus sp.) riding a Purple jellyfish (Pelagia noctiluca), at night in surface waters of the deep ocean off Kailua Kona, Hawaii, USA. August. The larval crustacea...

Doug Perrine / Phyllosoma larva of Spiny lobster (Palinurus sp) riding a Purple jellyfish (Pelagia noctiluca), at night in surface waters of the deep ocean off Kailua Kona, Hawaii, August. The larval crustacean use...

Doug Wechsler / Spectacled bear (Tremarctos ornatus) among Achupalla bromeliads a major food source; Antisanilla Reserve, Ecuador.

Doug Wechsler / Spectacled bear (Tremarctos ornatus) among Achupalla bromeliads a major food source; Antisanilla Reserve, Ecuador.

Staffan Widstrand / Nutmeg (Myristica fragrans) covering (or aril) which is the source of the spice Mace,near Lobo village, Triton Bay, mainland New Guinea, Western Papua, Indonesian New Guinea

Alan Williams / Lake Glaslyn showing the outflow the source of the Afon (River) Glaslyn with the summit of Mount Snowdon covered in cloud in the background, Snowdonia National Park, North Wales, UK, March.

Rhonda Klevansky / Monk crossing Lake Tana, source of the Blue Nile, from Debra Mariam Monastery to the mainland. Lake Tana Biosphere Reserve, Ethiopia. April 2015.