Post on 02-Jan-2016
Chapter 34Section 2
Phylum Nematoda & Rotifera
Phylum Nematoda• Roundworms (pseudocoelomates)
• Bilaterally symmetrical
• 1mm-120mm (4 feet)
• Digestive tract with two openings (mouth & anus)
• Cuticle- protective covering
Phylum Nematoda• Most are parasites and more than
50 species are parasites in humans
• Common roundworm studied by scientists in developmental biology is C. elegans
Ascaris• Genus of roundworm parasites
that live in pigs, horses, and humans
• Feed on food in intestines of host
• Females produce 200,000 eggs per day
Hookworms• Hookworm- intestinal parasite
• Have cutting plates that clamp onto the intestinal wall
• Feed on host’s blood
• Cause anemia• Like Ascaris, hookworms release
eggs • http://animal.discovery.com/tv-shows/monsters-inside-me/videos/flesh-eating-hookworm.htm• http://www.petsandparasites.org/dog-owners/hookworms
Trichinella• Form cysts in muscle of host
• Found in undercooked meat
• Trichinosis- disease causes muscle pain & stiffness
• Farmers no longer feed meat to hogs and freeze meat
Other Parasitic Roundworms
• Pinworm- most common roundworm parasite in the USA
• School age children
• Does not cause serious damage
• Found in feces
Other Parasitic Roundworms
• Filarial worms- disease-causing roundworms that infect over 250 million people in tropical countries
• Causes elephantiasis- limbs become swollen and skin hardens and thickens
• http://animal.discovery.com/tv-shows/monsters-inside-me/videos/parasite-causes-elephantiasis.htm
Other Parasitic Roundworms
• Dogs & cats
• T. canis and T. cati
• Live in the heart and large arteries of the lungs
• Heartworm disease
Phylum Rotifera• Rotifers
• Transparent, free-living animals that live in freshwater
• Cilia surrounds the mouth- helps sweep food in- algae, bacteria, & protozoa
Phylum Rotifera• Food moves from mouth to
mastax- muscular organ that breaks down food
• Food is absorbed then passes from intestines to cloaca- common hole which reproduction, digestion, and excretory systems empty
Phylum Rotifera• Rotifer reproduction
• Parthenogenesis- unfertilized eggs develop into adult females
• Other eggs form into males and the males fertilize other eggs with sperm
REVIEW!!!• Identify two characteristics of the
Phylum Nematoda and the Phylum Rotifera.
• What is the name of the most common roundworm studied by scientists in developmental biology?
• What type of worm causes elephantiasis?