Mark Siddall, a.k.a. Dr. Leech, says that while searching for the giant Amazonian leech, bloodsucking creatures were the least of his problems.

Produced by David Levin. Interview conducted by Peter Tyson. NOVA is produced by WGBH in Boston. Major funding for NOVA scienceNOW is provided by Pfizer, the National Science Foundation, the Howard Hughes Medical Institute, the Alfred P. Sloan Foundation, and public television viewers.

This material is based upon work supported by the National Science Foundation under Grant No. 0229297. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

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