In this Oct. 14, 2013 file photo, ecology professor Ricardo Freitas, left, and biology student Camila Scalzer catch a broad-snouted caiman to examine and release into the Marapendi Lagoon in Rio de Janeiro, Brazil. Freitas himself has grabbed and tagged 400 of the reptiles over the past decade. Sometimes he wades into the toxic sludge, slips a metal lasso around their heads and taps expertly on their snapping jaws until he's able to tape them shut. (Photo by Felipe Dana/AP Photo)
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