Worm

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A worm is any of numerous relatively small elongated soft-bodied invertebrate animals. The most famous is

Illustration of a tapeworm provided by Classroom Clip Art

the earthworm, a member of phylum Annelida, but there are hundreds of thousands of different species that live in a wide variety of habitats other than soil.

Originally, the word referred to any creeping or a crawling animal of any kind or size, such as a serpent, caterpillar, snail, or the like. Later this definition was narrowed to the modern definition which still includes several different animal groups. Major phyla include:

• Annelida (segmented worms)
• Sipuncula (peanut worms)
• Onychophora (velvet worms)
• Acanthocephala (spiny-headed worms)
• Nematoda (roundworms)
• Nematomorpha (horsehair worms)
• Nemertea (ribbonworms)
• Platyhelminthes (flatworms)
• Gnathostomulida (jaw worms)
• Chaetognatha (arrow worms)