Roundworms Brittney Jackson, Kaylee Kraft, Jessica Lin

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

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

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

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

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

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

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

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

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

Ascaris 10 inches long adult life in human intestine separate sexes female can produce up to 200,000 eggs a day o leave human body with feces  human waste as fertilizer, encourages the parasite 1.eggs hatch in the intestine 2.larvae burrow through the intestinal wall into blood or lymph vessels 3.carried through the heart and lungs (cause damage) 4.eventually go back to the small intestine where they settle and mature

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

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 o if not, the larvae are not freed from their cysts and eventually die cysts are calcified and remain in the muscles o cause stiffness

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 o causes itchiness the eggs may be distributed through the air and therefore around the house

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