Ribbonworms, Ribbonworms, Roundworms, and Roundworms, and

RotifersRotifers

Phylum Rhynchocoela Phylum Rhynchocoela (Ribbon-worm)(Ribbon-worm)

Longest wormLongest worm Free living, marineFree living, marine Long proboscis (muscular thin tube that Long proboscis (muscular thin tube that

thrust out to capture prey)thrust out to capture prey) AcoelomateAcoelomate no body cavity no body cavity Digestive tube with opening at both ends Digestive tube with opening at both ends Have circulatory systemHave circulatory system Thought to have evolved from flatwormsThought to have evolved from flatworms

Nematode (Round-worm)Nematode (Round-worm)

Bodies shaped like sharpened pencilBodies shaped like sharpened pencil Free living, active huntersFree living, active hunters Have a complete gutHave a complete gut Most parasiticMost parasitic Separate sexes- diecousSeparate sexes- diecous

It is thought that eggs could last It is thought that eggs could last thousands of yearsthousands of years

NematodesNematodes

May be most important animal groupMay be most important animal group They are everywhereThey are everywhere 1 apple – 50,000 to 90,000 (no such 1 apple – 50,000 to 90,000 (no such

thing as a vegetarian)thing as a vegetarian) Bilateral symmetryBilateral symmetry No cilia or flagella – only amebodeNo cilia or flagella – only amebode

NematodesNematodes

PseudocoelomPseudocoelom body cavity located body cavity located between endoderm and mesodermbetween endoderm and mesoderm This evolution of a body cavity allows This evolution of a body cavity allows

forfor Circulation but no heartCirculation but no heart Movement-makes body more rigidMovement-makes body more rigid Organ function-body organs can function Organ function-body organs can function

without being distortedwithout being distorted

AscarisAscaris AscarisAscaris can infect humans-eggs in soil can infect humans-eggs in soil

for years-eggs get into blood and is for years-eggs get into blood and is carried to the lungs where the larva cause carried to the lungs where the larva cause respiratory distress and can also get in respiratory distress and can also get in your intestinesyour intestines Most common human worm infectionMost common human worm infection

Common in tropical and subtropical areas Common in tropical and subtropical areas where sanitation and hygiene are poor.where sanitation and hygiene are poor.

Past by human or pig fecal materialPast by human or pig fecal material

NecatorNecator NecatorNecator Hookworm-moist soils of the tropics- Hookworm-moist soils of the tropics-

bores into soles of the feet-causes anemiabores into soles of the feet-causes anemia Infects host when an infective larva Infects host when an infective larva

penetrates the host's skin. The juvenile worm penetrates the host's skin. The juvenile worm migrates through the host's body and finally migrates through the host's body and finally ends up in the host's small intestine where it ends up in the host's small intestine where it grows to sexual maturity. grows to sexual maturity.

A hookworm’s mouthparts are modified into A hookworm’s mouthparts are modified into cutting plates. Attachment of hookworms to cutting plates. Attachment of hookworms to the host's small intestine causes on form of the host's small intestine causes on form of hemorrhages, and the hookworms feed on hemorrhages, and the hookworms feed on the host's blood. the host's blood.

TrichinellaTrichinella TrichinellaTrichinella found in pigs-can infect humans if found in pigs-can infect humans if

eat pork that isn’t cooked well-infects muscles in eat pork that isn’t cooked well-infects muscles in humanshumans Worse than eating raw chickenWorse than eating raw chicken

Mealy grainy pork – DON’T EAT!!!!!!!!!!!!!Mealy grainy pork – DON’T EAT!!!!!!!!!!!!! Higher in prevalence in people living in parts Higher in prevalence in people living in parts

of Europe, Asia, and Southeast Asia than in of Europe, Asia, and Southeast Asia than in the United States.the United States.

The life cycle is completed with the larvae The life cycle is completed with the larvae encysting in striated muscle, hence why you encysting in striated muscle, hence why you can get it by eating uncooked meat.can get it by eating uncooked meat.

Causes fever, edema, muscle weakness and Causes fever, edema, muscle weakness and tenderness tenderness

PinwormPinworm

PinwormPinworm females crawl out of anus and females crawl out of anus and lay eggs-50% of college students have lay eggs-50% of college students have pinworm at sometime.pinworm at sometime. Intestinal infectionIntestinal infection Biggest symptom is an itchy buttBiggest symptom is an itchy butt

FilarialFilarial

Filarial wormsFilarial worms cause elephantitis- cause elephantitis- enlargement of body parts due to blocked enlargement of body parts due to blocked ducts. ducts. Mosquitoes are reservoir hostMosquitoes are reservoir host Infects 120 million people a year, Infects 120 million people a year,

infects mostly in India, Africa and Asia. infects mostly in India, Africa and Asia. These worms lodge in the lymphatic These worms lodge in the lymphatic

system, the network of nodes and system, the network of nodes and vessels.vessels.

RotifersRotifers

Free swimming hunters (mostly freshwater Free swimming hunters (mostly freshwater that is still)that is still)

Swim with cilia- crown head called CoronaSwim with cilia- crown head called Corona Makes them appear to whirl like a wheel Makes them appear to whirl like a wheel

Feed on bacteria and protistFeed on bacteria and protist Some species have been known to be Some species have been known to be

cannibalistic cannibalistic One way gutOne way gut PseudocoelomPseudocoelom 99% female99% female

HomeworkHomework

1.1. Why might it be accurate to Why might it be accurate to describe ribbonworms as a describe ribbonworms as a transitional group between transitional group between flatworms and roundworms?flatworms and roundworms?

2.2. Compare and contrast ascaris and Compare and contrast ascaris and necator.necator.