Roundworms

Phylum Nematoda 1.Nematodes: roundworms 2.Nemata- “ thread” 3.Bilateral symmetry 4.Tube within a tube structure-mouth and anus 5.3 germ layers w/ pseudocoelom 6.Smaller than flatworms, taper at both ends

3 PseudocoelomatePseudocoelomate EctodermMesodermEndoderm Fluid filled cavity between the endoderm and ectoderm- pseudocoelom Differs from a true coelom because…. It is not entirely lined with mesoderm tissue Organs are not suspended or attached to membranes (mesenteries)

Lifestyle Lifestyle 1.Thick outer covering (cuticle) to protect them from harsh environment ex. Stomach acid 2.Move bodies with thrashing motion 3.Free living-Decomposers and predators (tremendously abundant) 4.Parasitic- ex. Ascaris, hookworm, heartworm-host is dog 5.Sexually reproduce: most are separate sexesmost are separate sexes some species are hermaphroditessome species are hermaphrodites

5 Nematodes  Found everywhere  Soil  Oceans  Polar ice  Hot springs  Parasites of nearly all plant and animal species!

Body Systems  No Respiratory or Circulatory Systems- limits size of worm due to distribution of nutrients via osmosis and diffusion  Complete Digestive  Nervous  Muscular  Excretory  Reproductive

Digestive System Complete Digestive Tract-  Mouth  Pharynx  Intestine  anus

Muscular System  Longitudinal muscles only  creates thrashing movement

9 Nervous System Nerve ring – “brain” Dorsal and ventral nerve cords

Excretory System  Excretory cells  Ducts  pores

11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nematode Reproductive Systems

12 Dioecious- separate sexes

Life cycles of parasitic roundworms ASCARIS lives in intestines and feeds off bloodlives in intestines and feeds off blood ingest eggs from dirty hands or unwashed veggies contaminated with fecal matteringest eggs from dirty hands or unwashed veggies contaminated with fecal matter eggs hatch in intestines and enter bloodstreameggs hatch in intestines and enter bloodstream larval worms bore into lungs, must be coughed up and swallowedlarval worms bore into lungs, must be coughed up and swallowed move to intestines where they maturemove to intestines where they mature

TRICHINELLA bore into muscles causing painful cysts or live in intestinesbore into muscles causing painful cysts or live in intestines ingest cysts in undercooked/raw meat (usually pork) ingest cysts in undercooked/raw meat (usually pork) cysts open up in intestines and reproduce therecysts open up in intestines and reproduce there larvae move into muscle tissue and form cysts larvae move into muscle tissue and form cysts

HOOKWORMS HOOKWORMS lives in intestineslives in intestines feeds on blood, causes major damage to intestinesfeeds on blood, causes major damage to intestines eggs deposited on soil from contaminated wasteseggs deposited on soil from contaminated wastes larvae live in soillarvae live in soil burrow into feet or exposed skin of hostburrow into feet or exposed skin of host larvae travel through bloodstream, to lungs, coughed up, swallowedlarvae travel through bloodstream, to lungs, coughed up, swallowed attach to intestinal wall where they matureattach to intestinal wall where they mature

PINWORMS most commonly infects childrenmost commonly infects children lives in intestineslives in intestines ingest eggs from contaminated soil or sandingest eggs from contaminated soil or sand hatch in intestineshatch in intestines female lays eggs near anus at night causing severe itchingfemale lays eggs near anus at night causing severe itching

18 Wuchereria bancrofti  Lives in lymphatic system  Obstruct lymph to cause swelling  Elephantiasis

19 Elephantiasis

20 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Source: Redrawn From Centers for Disease Control, Atlanta, GA. Fig Life Cycle of Wucheria spp.

21 Loa loa  Eye worm

22

23 Dracunculus medinesis  Fiery serpent

24

25 Dirofilaria immitis  Dog heart worm

26

27 The End