Definition of "flatworms" [flatworms]

• Plural form of flatworm. (noun)

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• "Platyhelminths - Also known as flatworms, members of this phylum are flattened, soft-bodied invertebrates ranging in size from microscopic to more than 50 feet (15 meters) in length."
• "In the context of this thread, the homeobox regulatory mechanism of non-metameric ancestral metazoans (such as flatworms) would qualify as an exaptation for the homeobox regulatory mechanism of their metameric descendants."
• "However, lower invertebrates, such as flatworms, have developed almost as complex an organ as that of the human male penis - with a seminal vesicle, a prostate gland and ejaculatory duct."