Roundworms

1. Roundworms Brittney Jackson, Kaylee Kraft, Jessica Lin

2. Basic Information • Phylum Nematoda • Key roles in decomposition and nutrient recycling • Habitat:  soil, marine, freshwater sediment • More than 15,000 species • Most are free living  • Parasites in animals and plants

3. Roundworm Bodies • Microscopic bodies • Movements produced by contraction of longitudinal muscles • Elongated, cylindrical, threadlike body which is pointed at both ends and covered by a tough, flexible cuticle • Cuticle gives nematode body shape and protection • Epidermis not composed of distinct cells •  Beneath epidermis is a layer of longitudinal muscles • No circular muscles present in the body wall • Fluid filled pseudocoelom (fluid filled cavity that contains transports nutrients) that serves as a hydrostatic skeleton • Bilateral symmetry, complete digestive tract, complete digestive tract, three definite tissue layers, and definite organ systems

4. Roundworm Bodies Continued • Lack specific circulatory structures • Sexes are usually seperate • Male is smaller than the female • Absence of a well-defined head

5. Gas Exchange/ secretion • no circulatory system • gas exchange and secretion by diffusion

6. Response to Stimuli • Sensory Organs • sensory hairs and papillae over the entire body •  Amphids- located on the head; small cavities; function as chemical receptors • Nervous System • 4 main nerves • entire length of the body • dorsal nerve • controls muscle movement • lateral nerves • sensory information • ventral nerve • motor skills • Brain •  rings of the four primary nerves • motor responses • move to or away from stimuli

7. Movement • thrash around • coil and uncoil  • movement produced by the longitudinal muscles

8. Classification and Evolution • Traditionally classified as a single phylum based on wormlike body strucutre • Molecular evidence suggests roundworms evolved from complex animals by a simplification of their bodies • Probably related to arthropods and can be classified as Ecdysozoa since like other arthropods/ecdysozoans they shed their cuticles periodically

9. Diseases • Ascariasis • Symptoms: coughing, shortness of breath, weight loss, nausea, blood in stool, worms in stool • Cause: contaminated food/water, Ascaris ( white worm) • Guinea worm disease • Symptoms: start a year after infection when the worm is ready to lay eggs, which emerges through the skin producing a painful blister • Cause: contaminated water • Loiasis • Symptoms: itchy eyes, blurred vision, people see worms move across their eyes • Cause:  Loa loa transmitted by day-biting flies •  Lymphatic filariasis •  Symptoms: swelling/scarring of the legs/groin • Cause: mosquito bites • River blindness • Symptoms: itchy rash, lose skin pigment, lose vision • Cause: spread by day-biting flies, leading cause of worldwide blindnes

10. Diseases Continued • Trichinosis • Symptoms: diarrhea, high fever, muscle pain, sensitivity to light, headache, and pink eye • Cause: eating uncooked meat • Threadworm • Symptoms: nausea, diarrhea, fever, coughing up blood,  Guinea worm disease Ascariasis Lymphatic filariasis

11. Ascaris • 10 inches long • adult life in human intestine • separate sexes • female can produce up to 200,000 eggs a day • leave human body with feces • human waste as fertilizer, encourages the parasite • eggs hatch in the intestine • larvae burrow through the intestinal wall into blood or lymph vessels • carried through the heart and lungs (cause damage) • eventually go back to the small intestine where they settle and mature

12. Hookworm • less than 1.5 cm • live in the human intestine • larvae hatch and feed on bacteria in the soil • host walks barefoot; microscopic larvae burrow into the skin; then enter the bloodstream • move to the intestine for maturation • hook onto the lining of the intestine and suck the blood

13. Trichina Worm • can live in pigs, rats, and bears • infection occurs in humans by eating raw or undercooked meat • live in the small intestine • larvae migrate to the skeletal muscle and encyst • in order to survive the host needs to be eaten • if not, the larvae are not freed from their cysts and eventually die • cysts are calcified and remain in the muscles • cause stiffness

14. Pinworms • found commonly in children • ingested by eating with hands contaminated with the small eggs • live in the large intestine • female worms move to the anal region to deposit the eggs • causes itchiness • the eggs may be distributed through the air and therefore around the house

15. Reproduction • sexual • Female: ovary, oviduct, uterus (fertilized here) • Male:sperm cells made in the testis, sperm cells pass through the spicule   • eggs deposited into the soil after fertilization