The wiggly world of wild and wonderful worms

 Kingdom: Animalia  Phylum : Platyhelminthes (Flatworms)  Class: Turbellaria (Turbellarians)  Class: Cestoda (Tapeworms)  Class: Trematoda (Flukes)  Phylum: Nematoda (Roudworms)  Family: Oxyuridae (Pinworms)  Family: Ancylostomatidae (Hookworms)  Family: Filariidae (Filarial Worms)  Family: Ascaridae (Ascarids)

 only a few cells thick  bilateral symmetry  muscles to move  no circulatory or respiratory system  have 3 tissue layers  ectoderm  mesoderm  endoderm  free-living or parasitic p.663

 cephalization – nerve bundling at one end  primitive “head”  two main nerves  acoelomate – lack of a true body cavity  one body opening  hermaphrodite – have both male and female reproductive cells  sexual reproduction (don’t self-fertilize)  asexual reproduction (by fragmentation) “head” p.664 Planarian (Turbellarian)

 marine  most are predators  some move with cilia in addition to muscles p.665

 endoparasites in intestine of host  1mm – 10m long  hooks and suckers for attachment to host  absorb nutrients through their skin  proglottid – body segment with reproductive organs that break off when mature p.665

 endoparasites in intestine or ectoparasites on fishes  tegument – protective outer layer  hooks and suckers for attachment to host p.666

Schistosoma - blood fluke 4-stage life cycle  eggs are found in water (Africa, Asia, S.America)  first larval stage enter intermediate host (snails)  second larval stage can reproduce asexually  larvae enter human host through skin or ingestion and cause damage to liver and intestine (schistosomiasis)  eggs are shed in urine and feces

 Kingdom: Animalia  Phylum : Platyhelminthes (Flatworms)  Class: Turbellaria (Turbellarians)  Class: Cestoda (Tapeworms)  Class: Trematoda (Flukes)  Phylum: Nematoda (Roudworms)  Family: Oxyuridae (Pinworms)  Family: Ancylostomatidae (Hookworms)  Family: Filariidae (Filarial Worms)  Family: Ascaridae (Ascarids)

 round in cross-section  bilateral symmetry  better muscle movement than flatworms  has 3 tissue layers  ectoderm  mesoderm  endoderm  free-living or parasitic

 cephelization – nerve bundling at one end  primitive “head”  two main nerves  pseudocoelom  two body openings  acts as circulatory system (nutrients and oxygen)  separate sexes  sexual reproduction

 1 cm long  50% of school age kids have had it  itching around anus  fecal- oral transmission (from feces to mouth)

 1/5 of world population affected  can cause mild diarrhea/ cramps/ anemia  larvae enter through bare feet  move through bloodstream, into lungs, into intestine  attach and suck blood

 live in blood or lymphatic system  mosquito vector  some cause elephantiasis  lymphatic fluid collects in tissues  some cause heartworm in dogs  weakness and fatigue, can lead to death

 most common human worm infection  contracted through contaminated food/water  lives in intestine of pigs/horses/humans  can cause blockage  feed on host’s food  eggs shed through feces and can live in soil for many years