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planarian
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planarian Diagram of the flatworm Planaria showing its nervous system, including labeled cerebral ganglia, longitudinal nerve cords, transverse commissures, and peripheral nerve plexus. An inset shows the flatworm's overall shape. Illustrations of various invertebrate animals are shown, including a freshwater sponge, sea anemone, sea gooseberry, planarian, whelk, sea urchin, earthworm, centipede, fly, crab spider, and crawfish.
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planarian
planarian Planarians are usually about 3 to 15 mm (0.1 to 0.6 inch) long; however, some grow to more than 30 cm (about 1 foot) long.

planarian

flatworm
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Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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planarian, (class Turbellaria), any of a group of widely distributed, mostly free-living flatworms of the class Turbellaria (phylum Platyhelminthes). Planaria is the name of one genus, but the name planarian is used to designate any member of the family Planariidae and related families. Most planarians occur in fresh water and are sometimes seen in large masses; some species are marine, others are terrestrial. Some species are parasitic; i.e., they obtain nourishment from the body of...

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