Roundworms and Rotifers PDF

ROUNDWORMS AND ROTIFERS Chapter 25 Section 2  LEARNING OBJECTIVES By the end of the lesson: Students can define the general characteristics of a roundworms. Students can analyze the movement of roundworms Vocabulary Review New cilia...

ROUNDWORMS AND ROTIFERS Chapter 25 Section 2  LEARNING OBJECTIVES By the end of the lesson: Students can define the general characteristics of a roundworms. Students can analyze the movement of roundworms Vocabulary Review New cilia hydrostatic skeleton trichinosis Copyright © McGraw-Hill Education Roundworms and Rotifers Essential Questions What are the similarities between the features of roundworms and flatworms? How can roundworms be identified based on movement? What are the ways humans risk contracting roundworm parasites? Roundworms and rotifers have a more highly evolved gut than flatworms. Copyright © McGraw-Hill Education Roundworms and Rotifers  Y2Mate.is - Nematoda Facts ROUNDWORM Facts an Body Structure of Roundworms Roundworms are in phylum Nematoda, and often called nematodes. Pseudocoelomates, bilaterally symmetric, cylindrical, unsegmented worms. Found in marine, freshwater, and on land. Can be parasitic or free-living. Vary in size Copyright © McGraw-Hill Education Roundworms and Rotifers Body Structure of Roundworms Feeding and digestion Most roundworms are free-living, but some are parasites. Some free-living are predators while others feed on decaying plants and animals Have a one-way digestive tract, a major evolutionary step associated with pseudocoelomates. Food enters through the mouth and wastes are leaving through the anus Copyright © McGraw-Hill Education Roundworms and Rotifers Body Structure of Roundworms Respiration, circulation, excretion, and response to stimuli No circulatory or respiratory organs, depend on diffusion Most roundworms exchange gases/excrete wastes through their outer body coverings. More complex forms have excretory ducts while others have flame cells. Nematodes have ganglia and associated nerve cords. Respond to touch, chemicals, and some respond to light and dark Copyright © McGraw-Hill Education Roundworms and Rotifers Body Structure of Roundworms Movement Muscles run the length of the roundworm’s body The muscles pull against the outside body wall and the pseudocoelom, which acts as a hydrostatic skeleton, fluid within a closed space that provides rigid support. Copyright © McGraw-Hill Education Roundworms and Rotifers  LEARNING OBJECTIVES By the end of the lesson: Students can define how roundworms reproduce Students can identify different classes of roundworms Body Structure of Roundworms Reproduction Roundworms reproduce sexually, with internal fertilization. In free-living worms, larvae hatch from eggs and develop into adults. In parasitic worms, larval development is more complicated, and often involves various parts of the host body or more than one host. Caenorhabditis elegans (C. elegans) have only 959 cells, and zygotes mature to adults in just 3 days. Copyright © McGraw-Hill Education Roundworms and Rotifers Diversity of Roundworms Trichinella worms Cause a disease called trichinosis, contracted by eating raw or undercooked pork products Burrow into the intestines of hosts, such as humans, pigs, and other mammals. After hatching, burrow into muscles causing muscle pain. Hookworms Commonly contracted in warm climates by humans who walk barefoot over contaminated soils. Travels through the circulatory system to the lungs, then to the esophagus where it is swallowed and transported to the intestines. Prevented by wearing shoes Copyright © McGraw-Hill Education Roundworms and Rotifers Diversity of Roundworms Ascarid worms Most common worm infection in humans Contracted through unwashed vegetables or contaminated soils Controlled by carefully washing vegetables and hands Pinworms Most common nematode parasite in humans in the United States Spread most frequently among children Copyright © McGraw-Hill Education Roundworms and Rotifers Diversity of Roundworms Filarial worms Tropical parasites spread through mosquito intermediary Causes elephantiasis, swelling of the lymph system, in humans Controlled by controlling mosquitoes Source of heartworm in cats and dogs Copyright © McGraw-Hill Education Roundworms and Rotifers Diversity of Roundworms Nematodes in plants Some species of roundworm cause disease in plants Most species of nematodes are harmless or beneficial to plants Can be used as biological control for pests. Copyright © McGraw-Hill Education Roundworms and Rotifers  LEARNING OBJECTIVES By the end of the lesson: Students can identify Rotifers Students can explain the purpose of cilia in rotifers Rotifers Rotifer features and movement Bilaterally symmetric pseudocoelomates with rings of cilia around their mouths Move through the water by means of their cilia Posterior end has “toes” that secrete an adhesive material that allows them to attach themselves to surfaces Copyright © McGraw-Hill Education Roundworms and Rotifers Rotifers Organ systems of rotifers Gather food with cilia and transfer it to a complete digestive tract Exchange gases and excrete metabolic wastes through diffusion Have sensory bristles and an eyespot Reproduce both sexually and asexually depending on environmental conditions Copyright © McGraw-Hill Education Roundworms and Rotifers Review Essential Questions What are the similarities between the features of roundworms and flatworms? How can roundworms be identified based on movement? What are the ways humans risk contracting roundworm parasites? Vocabulary hydrostatic skeleton trichinosis Copyright © McGraw-Hill Education Roundworms and Rotifers