Will Burrard-Lucas / Young male melanistic leopard (Panthera pardus), Laikipia Wilderness Camp, Kenya. Photographed with a camera trap. EDITORIAL USE ONLY. All other uses require clearance

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Nick Garbutt / Pack of wolves (Canis lupus). Yellowstone National Park, Wyoming, USA. January.

Will Burrard-Lucas / Young male melanistic leopard (Panthera pardus), Laikipia Wilderness Camp, Kenya. Photographed with a camera trap. EDITORIAL USE ONLY. All other uses require clearance

Will Burrard-Lucas / Young male melanistic leopard (Panthera pardus), Laikipia Wilderness Camp, Kenya. Photographed with a camera trap. EDITORIAL USE ONLY. All other uses require clearance

Will Burrard-Lucas / Young male melanistic leopard (Panthera pardus), Laikipia Wilderness Camp, Kenya. Photographed with a camera trap.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding and digging in snow whilst hunting, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Giri Cavale / Melanistic leopard / Black panther (Panthera pardus) on territorial patrol on track, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Ingo Arndt / Land snail (Polymita picta) collection of shells showing variation in patterning, Cuba. Endemic species.

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

MYN / JP Lawrence / Dyeing poison frog (Dendrobates tinctorius) captive, occurs in Guiana, Suriname, Brazil, and French Guiana. Meetyourneighbours.net project

MYN / JP Lawrence / Dyeing poison frog (Dendrobates tinctorius) captive, occurs in Guiana, Suriname, Brazil, and French Guiana. Meetyourneighbours.net project

Charlie Summers / Black Jaguar (Panthera onca) kitten, captive.

Sven Zacek / Hepatica (Hepatica nobilis) white morph and normal blue morph, Southern Estonia, April.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) mother with rare white furred baby, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) rare white furred baby jumping, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) rare white furred baby calling, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) rare white furred baby playing with another baby. Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) mother with rare white furred male baby, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) rare white furred baby playing with flower, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) mother with rare white furred baby, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) mother carrying rare white furred baby on belly, Jigokudani Valley, Nagano Prefecture, Japan. June.

Yukihiro Fukuda / Japanese macaque (Macaca fuscata fuscata) mother with rare white furred baby, Jigokudani Valley, Nagano Prefecture, Japan. June.

Espen Bergersen / Common guillemot (Uria aalge) calling, bridled guillemot morph with white ring around the eye, Hornoya bird cliff, Finnmark, Norway. March.

Andy Trowbridge / Arctic Fox cub (Alopex / Vulpes lagopus) standing in fresh snow, blue morph. Dovrefjell National Park, Norway, September.

Juan Carlos Munoz / Black howler monkeys (Alouatta caraya) male and two females calling from tree, captive, Apenheul Park, Netherlands.

Nick Garbutt / Three Mossy Leaf-tailed Geckos (Uroplatus sikorae) in differing colour morphs. From forest understorey at night. Masoala National Park, Madagascar. Photographed on white background

Dietmar Nill / Laboratory mice (Mus musculus) showing colour variation / morphs

Sergio Hanquet / Purple sea urchin (Sphaerechinus granularis), three of different colours. Tenerife, Canary Islands.

Ben Cranke / Lion (Panthera leo) female and cubs, one cubs a leucistic white male. Greater Kruger National Park, South Africa.

Melvin Grey / Blue tit (Cyanistes caeruleus), two feeding on fat ball, one leucistic. Carmarthenshire, Wales, UK. August.

Melvin Grey / Senegal thicknee (Burhinus senegalensis), leucistic. Gambia, Africa.

Felis Images / Melanistic leopard / Black panther (Panthera pardus fusca) sitting, reflected in water. Nagarhole National Park, India. Photo Phillip Ross/Felis Images

Felis Images / Melanistic leopard / Black panther (Panthera pardus fusca) drinking, reflected in water. Nagarhole National Park, India. Photo Phillip Ross/Felis Images

Felis Images / Melanistic leopard / Black panther (Panthera pardus fusca) resting in tree. Nagarhole National Park, India. Photo Phillip Ross/Felis Images

Felis Images / Melanistic leopard / Black panther (Panthera pardus fusca) resting in tree. Nagarhole National Park, India. Andhra Pradesh, India. Photo Srikanth GP/Felis Images

David Tipling / Rare melanistic Grey seal (Halichoerus grypus) pup, Horsey, Norfolk, England, UK, February. Less than one in 400 pups born annually are melanistic, usually the pups are a creamy white in colour.

David Tipling / Rare melanistic Grey seal (Halichoerus grypus) pup, Horsey, Norfolk, England, UK, February. Less than one in 400 pups born annually are melanistic, usually the pups are a creamy white in colour.

David Tipling / Rare melanistic Grey seal (Halichoerus grypus) pup, Horsey, Norfolk. Less than one in 400 pups born annually are melanistic, usually the pups are a creamy white in colour.

Tony Wu / Japanese sea cucumber (Apostichopus japonicus), rare albino. Hokkaido, Japan. May.

Fabio Pupin / Western whip snake, (Hierophis viridiflavus), dark morph, basking in grass, Italy, April . Non-ex.

Fabio Pupin / Common adder, (Vipera berus), dark moprh, Alps, Italy, October . Non-ex.

Fabio Pupin / Common adder, (Vipera berus), dark moprh, Alps, Italy, October . Non-ex.

Fabio Pupin / Common wall lizard, (Podarcis muralis), rare melanic morph, Italy, April . Non-ex.

Fabio Pupin / Dalmatian wall lizard, (Podarcis melisellensis), fight between two males with distinct morphs, Croatia, April . Non-ex.

Jiri Lochman / Eastern quoll (Dasyurus viverrinus) black morph, Mount Field NP, Tasmania.

Jiri Lochman / Eastern quoll (Dasyurus viverrinus) black morph, Mount Field NP, Tasmania.

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Pair mating. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Alopex lagopus). blue colour morph in winter coat. Hornstrandir, Iceland. Photographed by camera trap.

Terry Whittaker / Arctic fox (Vulpes lagopus). blue colour morph. Hornstrandir Nature Reserve, Iceland. March.

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). White colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus) blue colour morph, on coast, Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Pair mating. Hornstrandir Nature Reserve, Iceland. March

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), pair within breeding colony in courtship, male melanistic. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) with melanism in breeding colony, male melanistic. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), melanistic male in breeding colony, portrait. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), melanistic male amongst others in breeding colony. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), melanistic male, portrait. Atka Bay, Antarctica. May.

Kerstin Hinze / Melanistic Common dormouse (Muscardinus avellanarius) resting on a branch, September. Captive

Bruno D'Amicis / Melanistic Asp viper (Vipera aspis) moving between the roots of ancient tree in old growth Beech (Fagus sylvatica) forest. Abruzzo, Lazio and Molise National Park / Parco Nazionale d'Abruzzo, Lazi...

Will Burrard-Lucas / Short film describing how photographer Will Burrard-Lucas photographed a melanistic Leopard (Panthera pardus), showing camera trap set-up, near Laikipia Wilderness Camp, Sosian Game Ranch, Kenya, Febr...

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) running in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) digging in snow, hunting, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) walking, carrying food in its mouth, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) sitting on snow, looking around and sniffing, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Wide angle shot of two Arctic foxes (Vulpes lagopus) running over rocks and snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Wide angle shot of two Arctic foxes running (Vulpes lagopus) in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Two Arctic foxes (Vulpes lagopus) resting in snow before getting up and leaving the frame, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Karine Aigner / Reddish egret (Egretta rufescens) white morph wading in water. Cat Island, Bahamas.

John Cancalosi / White-tailed deer (Odocoileus virginianus), leucistic white doe, New York, USA, June.

John Cancalosi / White-tailed deer (Odocoileus virginianus), leucistic white doe, New York, USA, June.

John Cancalosi / White-tailed deer (Odocoileus virginianus), leucistic white doe, New York, USA, June.

Sandesh Kadur / Melanistic Leopard / Black panther (Panthera pardus) male in tree, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Giri Cavale / Melanistic leopard / Black panther (Panthera pardus) on territorial patrol on track, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Giri Cavale / Melanistic leopard / Black panther (Panthera pardus) male, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Giri Cavale / Melanistic leopard / Black panther (Panthera pardus) male in tree, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Giri Cavale / Melanistic leopard / Black panther (Panthera pardus) male in tree, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Giri Cavale / Melanistic leopard / Black panther (Panthera pardus) on territorial patrol on track, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Giri Cavale / Leopard (Panthera pardus) male chasing away a melanistic leopard / black panther, Nagarahole National Park, Nilgiri Biosphere Reserve, Karnataka, India.

Remi Masson / Albino Wels catfish (Silurus glanis) swimming in the River Rhone, France, November.

Felis Images / Leopard (Panthera pardus) spotted male with melanistic female resting on rocks, Tamil Nadu, Western Ghats, India.

Tony Heald / Southern giant petrel (Macronectes giganteus), white colour morph. Right Whale Bay, South Georgia. September.

Edwin Giesbers / White lion (Panthera leo) male. Captive, Netherlands.