The Mysterious Vanishing Frogs of North America
I have a passion for all things slimy, wet, and creepy-crawly. Some of the best times of my life have been spent on my knees, digging in the dirt for earthworms, traipsing back from ponds with buckets of putrid swamp water teeming with tadpoles, or chasing fat little toads in knee-high grass. I love the outdoors and all of the ugly animals that inhabit it. I like to catch them, watch them, and – especially – photograph them. For the longest time, lizards have been the main focus of my photographic endeavors, but last summer, inspired by a book on frogs from the local library, I set out to document the lives of these often overlooked amphibians. I live in southern Florida near the Everglades, and I remember catching, mating, and raising dozens of frogs as a kid, so I didn’t expect to have to lug my tripod and lenses very far to find a suitable subject. But much to my dismay, I didn’t find a single frog in an entire afternoon of searching. In fact, in the year and half since my initial search, I’ve seen only four frogs.
I immediately assumed that pollution had decimated the populations of my favorite amphibian. I have no hard evidence, but I believe that this is a common belief shared by many fellow lay naturalists. This makes scientific sense; frogs spend most of their lives in water, have thin, easily permeable skin during all stages of their lives, and lay their gelatinous eggs in water. Pesticides and other pollutants accumulate in water, where they can easily diffuse into the thin skin of frogs. It all seems perfectly logical.
The catch is, this perfectly logical and widely believed answer is probably false. While there are never any absolutes in ecology, there is a l...
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Explanation for Naturally Occurring Supernumerary Limbs in Amphibians
Stanley K. Sessions and Stephen B. Ruth
The Journal of Experimental Zoology 254:38-47 (1990).
Sessions’ research group’s web page
Morphological Clues from Multilegged Frogs: Are Retinoids to Blame?
Stanley K. Sessions, R. Adam Franssen, and Vanessa L. Horner
Science 1999 April 30; 284: 800-802. (in Reports)
University of Wisconsin BioLab
Stanley K. Sessions
Science 1998 January 23; 279: 459 (in Letters)