SINCLAIR STAMMERS / Phase contrast photomicrograph of Blue green alga / Cyanobacteria (Spirulina platensis) each algal filament or Trichome is 5 microns in diameter.

Jane Burton / Spotted seahorse {Hippocampus kuda} light colour phase, note eyes rotating independantly from each other, captive, from Indo-Pacific

TOM MANGELSEN / Stoat / Ermine in winter coat by wood pile (Mustela erminea) Grand Teton NP, USA

Tom Vezo / Grey wolves showing fur colour variation. (Canis lupus)

Constantinos Petrinos / Ribbon eel in male blue phase {Rhinomuraena quaesita} Sulawesi, Indonesia - species is hermaphrodite changing sex from male to female; juveniles are black, male is blue underneath , and final female p...

Konrad Wothe / Snow Geese (Chen caerulescens atlanticus / Chen caerulescens) in flight, white and grey phase, Bosque del Apache, New Mexico, USA, November

Barry Mansell / Ornate chorus frog (Pseudacris ornata) brown and green colour phase, West Florida, USA

Charlie Summers / Two Tawny eagles (Aquila rapax) one in light phase and the other in dark phase, perched on tree branch, Kgalagadi TB Park of South Africa

Tim Laman / Pygmy Seahorse (Hippocampus bargibanti) in yellow colour phase camouflaged in a yellow Sea Fan. West Papua, Indonesia, April 2007

Tim Laman / Pygmy Seahorse (Hippocampus bargibanti) in yellow colour phase camouflaged in a yellow Sea Fan. West Papua, Indonesia, April 2007

Steven Kazlowski / Portrait of Red fox (Vulpes vulpes) of silver / grey colour morph standing in snow, winter, Arctic coast of Alaska

Steven Kazlowski / Portrait of Red fox (Vulpes vulpes) of silver / grey colour morph standing in snow, winter, Arctic coast of Alaska

Steven Kazlowski / Portrait of Red fox (Vulpes vulpes) of silver / grey colour morph standing in snow, winter, Arctic coast of Alaska

Doug Perrine / Atlantic sailfish {Istiophorus albicans} feeds on sardine seized from bait ball of Spanish sardines / gilt sardine / pilchard / round sardinella {Sardinella aurita} off Yucatan Peninsula, Mexico, Cari...

Pete Oxford / Guineafowl Pufferfish (Arothron meleagris) in its golden phase, off Wolf Island in the northern archepelago, Galapagos Islands, Ecuador, South America

Jane Burton / Spotted seahorse {Hippocampus kuda} light colour phase, on coral reef, captive, from Indo-Pacific

Jane Burton / Spotted seahorse {Hippocampus kuda} dark colour phase, on coral reef, captive, from Indo-Pacific

Jane Burton / Spotted seahorse {Hippocampus kuda} light colour phase, head portrait, captive, from Indo-Pacific

Jane Burton / Spotted seahorse {Hippocampus kuda} light colour phase, on coral reef, captive, from Indo-Pacific

Jane Burton / Spotted seahorse {Hippocampus kuda} light colour phase, captive, from Indo-Pacific

Steven David Miller / Green anole {Anolis carolinensis} brown phase, on thorny stem. SW Florida, USA

John Cancalosi / White-tailed Deer (White colour phase) {Odocoileus virginianus} female, New York, USA. A rare colour phase resulting from double recessive white genes (not true albino)

John Cancalosi / White-tailed Deer (White colour phase) {Odocoileus virginianus} female with fawn, New York, USA. A rare colour phase resulting from double recessive white genes (not true albino)

John Cancalosi / White-tailed Deer (White colour phase) {Odocoileus virginianus} female, New York, USA. A rare colour phase resulting from double recessive white genes (not true albino)

Florian Graner / Guineafowl pufferfish, yellow phase (Arothron meleagris) Cocos Island, Costa Rica

Doug Perrine / Bicolor parrotfish {Cetoscarus bicolor} super male in terminal colour phase, feeding on coral, Great Barrier Reef, Queensland, Australia

Paul Hobson / Arctic skua brown phase {Stercorarius parasiticus} Handa Is, Scotland, UK

Jose Schell / Crossed phase American Red fox {Vulpes vulpes} standing in river. Anticosti Island, Canada.

Jose Schell / North American red fox - silver phase - covered in snow , {Vulpes vulpes} Canada

Jose Schell / North American red fox in crossed colour phase, Canada

Jose Schell / North American red fox in silver colour phase. Canada

Mike Wilkes / Reddish egrets in flight one white phase. Texas, USA

TOM MANGELSEN / Stoat / Ermine behind tree. (Mustela erminea) USA

Hans Christoph Kappel / Map butterfly - first brood of year in May/ June, Germany. First generation resemble small fritillary - dusky orange wings marked with black

Jose B. Ruiz / Rock pool blenny yellow colour phase {Parablennius sanguinolentus} Mediterranean

Jose B. Ruiz / Rock pool blenny yellow colour phase {Parablennius sanguinolentus} Mediterranean

Michael Durham / Blue phase of normally green Rose ringed parakeet {Psittacula krameri} female

Michael Durham / Blue phase of normally green Rose ringed parakeet {Psittacula krameri} female. Captive, USA.

TOM MANGELSEN / Stoat /Ermine in snow but in summer coat (Mustela erminea)

Robert Valentic / Three adult Puff adders, one in yellow phase {Bitis arietans} South Africa

Tom Vezo / Willow grouse (ptarmigan) male, Churchill, Manitoba Canada.

Tom Vezo / Willow grouse (ptarmigan) male, Churchill, Manitoba. Canada.

Constantinos Petrinos / Ribbon eel, adult blue phase, Sulawesi, Indonesia

Constantinos Petrinos / Ribbon eel, transitional colour phase, Sulawesi, Indonesia

Constantinos Petrinos / Ribbon eel, black juvenile phase, Sulawesi, Indonesia

Florian Graner / Guineafowl pufferfish, spotted phase {Arothron meleagris} Cocos Is, Costa Rica

Barry Mansell / Carolina pygmy rattlesnake, red phase {Sistrurus miliarus miliarus} North Carolina, US

Doug Perrine / Atlantic spotted dolphins juveniles without spots {Stenella frontalis} Bahamas (Non-ex).

Doug Allan / Arctic fox in blue phase {Vulpes lagopus} Svalbard, Norway

Tom Vezo / Grey squirrel (black phase) {Sciurus carolinensis} Vancouver, Canada

Paul Hobson / Arctic skua male light phase {Stercorarius parasiticus} Handa Is, Scotland, UK

Mike Wilkes / Reddish egrets in flight, one white phase. Texas, USA

Jeff Turner / Grey wolf (white arctic form) Ellesmere Island, Canada

PREMAPHOTOS / Agama lizard (Agama agama) male in breeding colours. Tanzania, East Africa

LYNN M. STONE / Stoat in winter snow. Minnesota, USA

Tom Vezo / Brown pelican portrait, La Jolla CA USA

Dave Watts / Eastern quoll, pale phase {Dasyurus viverrinus} Tasmania, Australia

Dave Watts / Eastern quoll, dark phase {Dasyurus viverrinus}Tasmania, Australia

Dave Watts / Eastern quoll, pale phase {Dasyurus viverrinus} Tasmania, Australia

LYNN M. STONE / Snow goose {Chen caerulescens} blue phase plumage, Illinois, USA.

Nature Production / Moth {Biston robustus} black colour phase and white cololur phase resting on tree trunk, Japan

LYNN M. STONE / Snow goose, blue phase. {Anser caerulescens} N Illinois, USA

Brian Lightfoot / Chaffinch with unusual pale coloration {Fringilla coelebs} Aviemore Scotland UK