Biology / Unit 10 Bio 2265 short lesson, about 20 seconds
Phylum Nematoda
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The idea
Nematodes are pseudocoelomate roundworms with a complete digestive tract running mouth to anus, among the most numerous animals on Earth by count.
In practice
Caenorhabditis elegans, a small free-living nematode, serves as a widely used model organism for animal development and genetics.
Where people slip
Most nematode species are free-living, not parasitic — parasitic species draw more attention but are a minority of the phylum's diversity.
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