Planaria Dugesia tigrina Platyhelminthes, Turbellaria

The phylum Platyhelminthes includes the so-called flat-worms, many of which are parasitic or marine. Most of the free-living, freshwater forms are planarians, and a few of these are large enough to be considered macroorganisms. 

Planarians are usually associated with the substrate of shallow waters. They are often found on the underside of rocks and detritus. Most are carnivores and scavengers that feed on a variety of soft invertebrates. 

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Perkins, C., and B. Fried Intraspecific Pairing of Planaria, Dugesia tigrina and D. dorotocephala (Platyhelminths Turbellaria), and Observations on Lipophilic Excretory-Secretory Worm Products. J. Chem. Ecol. 8, 901-909 (1982). 

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