Flat Worm and Round Worms!

Flatworms had it FIRST!! Phylum: Platyhelminthes Bilateral symmetry Directional motion = 1st active predator Cephalization – development of a ‘head end’ Ganglia: bundle of nerve cells make up a pre-brain Nerves concentrated at ‘head end’ since sensory cells were concentrated at that end Sensory nerves formed bundles = ganglion Eyespots detect light, Auricles detect chemicals ‘smell’ 2 nerve cords transmit info to rest of body

New Inovations in Excretory System Nitrogenous metabolic waste still removed by diffusion Protonephridia (NEW) flame cells help regulate solute concentration Evolve in to the nephrons of mammal kidneys

Flatworm Reproduction 1st internal fertilization Evolutionary advantage Make fewer gametes Save energy Hermaphrodites = make both eggs & sperm Evolutionary advantage = you can mate with any other member of your species that you can find!

Ancestral Traits Gastrovascular cavity for digestion & circulation Mouth in center of body Respiration (gas exchange) by diffusion

Free-living Flatworms = Class Turbellaria Marine Fresh-water

Flukes = Class Trematoda Parasites of blood and liver

Swimmer’s Itch =Schistosoma

Tape Worms = Class Cestoda

Human Tape Worm Sources =Under cooked Prevention Beef (N. America) Pork(S. America) Fish (Asia) Prevention Cook your meat!!! Wash your hands after using the restroom Don’t drink contaminated water

Round Worms = Phylum Nematoda 1st Animal with a body cavity =pseudocoelom Fake body cavity – just a space between layers. Pseudocoelom used as a Hydrostatic skeleton Longitudinal muscles only= thrashing

Types of body cavity (coelom) Acoelomate Pseudocoelomate Coelomate

Digestive Tract 1st Alimentary Canal = one way digestive tract with mouth at one end and an anus at the other Evolutionary advantage Specialization Can eat new meal before the old one is finished processing

Alimentary Canal

Spicule injects sperm for internal fertilization Spicule inside body Spicule extended

Ascaris…………………………… One of the most common parasite of humans Up to 64% of people in some S.eastern states Eggs injested on Vegetables or from Soil

Hookworm in Humans Eggs in feces reach the ground Juviniles live and grow in soil 2nd stage juviniles burrow into human skin They enter the bloodstream & travel to lungs Juvilinles are coughed up then swallowed They finish maturing in small intestine Adults in small intestine suck blood from intestine wall (may cause anemia) Common in Southern States

Heartworm Larva in Blood