Stephen Dalton / Close up of eye of Common green iguana (Iguana iguana)

Dr. Axel Gebauer / Red panda (Ailurus fulgens), close up of eye detail, captive

James Christensen / Ecuadorian Toad-headed Pit-viper (Bothrocophias campbelli) eye and pit sensory organ, Mindo, western slope of Andes, Ecuador

Murray Cooper / Fraser's Anole (Anolis fraseri) male eye, western slope of Andes

Thomas Marent / Tomato Frog (Dyscophus antongilii) eye, very rare in nature, only found in the town of Maroantsetra, Madagascar

Silvia Reiche / Eurasian Jackdaw (Corvus monedula), eye of chick, Hoogeloon, Netherlands

Thomas Marent / Green Tree Python (Chondropython viridis) close up of face showing vertical pupil and row of heat sensors, Lae, Papua New Guinea

Niall Benvie / Close-up of human girl's eye with pupil dilated

Christian Ziegler / Red-eyed Tree Frog (Agalychnis callidryas), the golden webbed skin is a nictitating membrane, part of the eye lid and enables the frog to see without giving up its camouflage

Christian Ziegler / Red-eyed Tree Frog (Agalychnis callidryas) detail of eye, Soberania National Park, Panama

Michael Durham / Human (Homo sapiens) detail of a nine year old boy's eye

Michael Durham / Allen's Swamp Monkey (Allenopithecus nigroviridis) detail of eyes, native to Africa

Piotr Naskrecki / Prominent (Notodontidae) moth caterpillar with false eye spot on rear, the black pupil like portion of the false eye spot against the red background resembles the eye of some toxic tree frogs, Costa R...

Claus Meyer / Cururu Toad (Bufo paracnemis) eye of female, Caatinga ecosystem, Brazil

Birgitte Wilms / Broadclub Cuttlefish (Sepia latimanus) detail of eye, 60 feet deep, Solomon Islands

Heidi & Hans-Juergen Koch / Colubrid Snake (Elaphe sp) close-up portrait showing use of tongue (Nasovomeral sense) to identify friend, enemy, or prey

Birgitte Wilms / Common Lionfish (Pterois volitans) detail of eye, 40 feet deep, Solomon Islands

Konrad Wothe / Domestic Cat (Felis catus) close-up of eye, Germany

PREMAPHOTOS / Giant / marine cane toad (Bufo marinus) at night, with the pupil of the eye constricted, Trinidad

PREMAPHOTOS / Giant / marine cane toad (Bufo marinus) at night, with the pupil of the eye dilated, Trinidad