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Chapter 34. Section 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.
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Chapter 34 Section 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
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
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?