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One Picture
One Picture


Photographers: Heidi and Hans-Juergen Koch
Subject: Glass frog
Where: Native to Venezuela
Camera: Nikon F5 with 105mm/Nikkor lens
Lighting: One Nikon S B-28 flash with softbox
Film: Fuji RDP
Exposure: 1/60th of a second at f11-16


You are looking at a female glass frog from the Venezuelan cloudforest with a belly full of eggs. Like this diminutive amphibian’s green bones, its organs are in plain view. Some scientists speculate that glass frogs have a pigment that reflects infrared radiation, which is invisible to human eyes. But since plants reflect the same wavelength of light, glass frogs clinging to foliage overhanging a swift mountain stream may be cloaked from the sight of predators such as pit vipers. Glass frogs breed throughout the year in habitats where there is little seasonal climate change. Males peep and trill through the night to attract mates and proclaim their territory, which might be a single leaf. The females, meanwhile, lay clutches of about 30 eggs on carefully chosen leaves from which the hatching tadpoles will drop right into the water.

Glass frogs (rana de cristal in Spanish) occur from southern Mexico to northern Argentina as well as in southeastern Brazil, and while scientists have described some 140 species, others await discovery. A recent Conservation International expedition, for example, found three new glass frogs in the mountains of Colombia. Most species fall into the size range of .07 to 1.2 inches, like this frog from Henri Pittier National Park on Venezuela’s northern coast, known only by the scientific name of Hyalinobatrachium antisthenesi. A rare exception is the Pacific giant glass frog of Andean Ecuador and Colombia, which can be 3.2 inches from snout to vent. The frogs’ bodies, usually some shade of green, are slender and fragile. And their legs are long and thin with webbed feet that end in large toe pads for climbing trees or, in some instances, clinging to rock faces behind waterfalls. Conservationists note that many glass frogs have a very limited range, making them particularly vulnerable to extinction.

The German-based husband-and-wife photography team of Heidi and Hans-Juergen Koch has traveled for 20 years in pursuit of unusual animal images for publications around the world. However, they made the glass frog picture above close to home for a feature in the magazine Stern. The Kochs wanted to pose this gravid female, which belonged to a frog specialist and breeder, on a glass pane to show its underside. But “the frog was an impatient model,” they relate, “and we didn’t want to stress this tiny sensitive creature. After a jump and a stroll on the carpet, we got our last chance—and we luckily got the shot we wanted.”—Les Line

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