Pseudocoelomate Animals body cavity present but incompletely lined
Pseudocoelomate Animals • body cavity present but incompletely lined with mesoderm • body cavity is fluid filled and acts like a hydrostatic skeleton • complete digestive tract with 2 openings
Now I can poop and eat at the same time !
There are 8 phyla of pseudocoelomate animals Phylum Nematoda - the Roundworms • smooth, long, tubular body • move with longitudinal muscles in body wall • dioecious • fluid filled pseudocoel – hydrostatic skeleton
Long, smooth and tubular
• rigid cuticle covering body • paired nerve cords – dorsal and ventral sides • free living and parasitic worms are in the phylum • 15, 000 species have been named; estimate 500, 000 species exist
Lo mein ? ? 10 inches
– large human roundworm • Southeastern US – more common • Intestinal worm – 30 cm long • eggs are in human feces and can directly infect another person via food • larvae develop and are carried by the blood to the lungs – cough/swallow
Ascaris Can cause pneumonia and intestinal blockage
Female posterior Ascaris Male posterior characteristic hooked end dioecious
Larval stage forms calcified cysts in muscle of host ( human or pig/bear ) Trichinosis – contracted from undercooke infected pork
Trichinella spiralis - infected, undercooked pork
Dirofliaria immitis • a parasitic nematode • that can kill your dog
Immature heartworm in blood
dog mature larvae immature larvae mosquito
Toxocara canis - roundworms found in puppies Another parasite
• common in southern states • adult worms live in intestines and suck blood • eggs leave in human wastes • larvae hatch in soil and penetrate bare skin • ingested worms travel to intestines, • then to lungs in bloodstream • worms are coughed up and swallowed • and become adult worms in intestines
Hookworm mouth
hooks
– itchy worms Fecal samples are used to diagnose most digestive system parasites
Pinworm eggs
Filarial worms – transmitted by a fly or mosquito Live in host’s lymphatic vessels
elephantiasis
River blindness Filarial worm - affecting 30 million people
Life cycle depends on a small “water flea” crustacean Infected “fleas” have worm larvae and get swallowed in drinking water Male and female worms grow and mate in host Female worm migrates to body surface to release eggs
Worm under skin
Guinea worm being “wound” out of skin
Parasitic plant nematodes annually destroy millions of dollars in crops
Poor root growth caused by parasitic nematodes on corn root
Crop damage to Canola bean crop in Australia estimated nematode crop damage $200 million/year
- Slides: 36