| Term | Definition |
|---|
| Acoelomate Taxa | first appearance of bilateral symmetry; cephalization; gut cavity rather than coelom; triploblastic |
| 3 germ layers | ectoderm, endoderm, mesoderm |
| Phylum Platyhelminthes | flatworms |
| Phylum Nemertea | ribbon worms |
| parenchyma | mesodermal; fills space between gut and ectoderm |
| level of organization | simple |
| major advances in: | nervous coordination and appearance of excretory system |
| Platyhelminthes | large range in size; body flattened dorsoventrally; free-living & parasitic forms exist |
| free living platyhelminthes | generally marine; some freshwater and terrestrial |
| parasitic platyhelminthes | endo and ectoparasites; often seek multiple hosts |
| platyhelminthes locomotion | cilia; dual gland organs for anchoring and release; multiple muscle layers |
| platyhelminthes digestion | mouth, pharynx, and intestine; exhibit both extracellular and intracellular digestion |
| platyhelminthes excretion | protonophridia; flame cells |
| flame cells | beat flagella to create negative osmotic pressure and regulate current |
| platyhelminthes nervous system | longitudinal nerve cords; "ladder pattern" of nerves; differentiation of neourons |
| platyhelminthes sense organs | ocelli (simple eyes); ear-like organs; chemical and mechanical receptors |
| platyhelminthes reproduction | asexual (fission/budding); asexual (monoecious) |
| 4 Classes of Platyhelminthes | turbellaria, trematoda, monogenea, & cestoda |
| Class Turbellaria | freeliving; locomotion via muscles and cilia; gliding via mucous from adhesive glands; further classified by gut or pharynx form |
| Class Trematoda | parasitic flukes; endoparasitic in vertebrates; lack cilia on epidermis; have suckers and hooks for adhesion |
| Subclass Digenea | subclass of trematoda; utilize intermediate and definitive hosts (molluscs and vertebrates); include liver flukes, blood flukes, and lung flukes |
| Class Monogenea | ectoparasites (mainly of fish); feed on body fluids (i.e. blood); only damaging in crowded conditions; have just one host |
| Class Cestoda | tapeworms; contain sets of reproductive organs (proglottids); microvilli absorb nutrients; contain suckers and hooks |
| Phylum Nemertea | ribbon worms; freeliving and marine; complete digestive system with anus |
| rhynchocoel | eversible proboscis in Nemertea body cavity |
| Phylum Nematoda (~15,000 species) | found in all habitats; free living or parasitic; cause $100 billion crop damage yearly in plants; impact almost all vertebrates |
| Nematoda structure | cyncytial epidermis covered by thick cuticle; hydrostatic pressure lends support |
| Nematoda locomotion | longitudinal muscles; capable of side-to-side motion |
| parasitic nematodes of humans | hookworm, pinworm, intestinal roundworm, trichina worm, whipworm |
| hookworm | burrows directly into skin |
| pinworm | most common; inhale eggs in dust/via fingers |
| intestinal roundworm | ingest eggs via contaminated vegetables; can reach 30cm in length |
| trichina worm | ingest juveniles in pork |
| whipworm | ingest in contaiminated food |
Combine with other sets
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