Nemata - roundworms, Trichina, filaria Slide 22 Invertebrates 5. Mollusca - snails, slugs, clams, and oysters 6. Annelida - segmented worms, leeches, earthworms Slide 23 Invertebrates 8. Arthropoda - insects, spiders, crayfish, millipedes Vertebrates 9. Segment 8 or 9 has a reproductive opening.
Individuals vary - Hereditary differences affect ability of organisms to survive and reproduce.