Flatworms

Phlylum Platyhelminthese = Flatworms

Flatworm FIRSTs!! Bilateral symmetry Directional motion = 1st mobile predator Cephalization – development of a head 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 Flatworm FIRSTs!!

New Innovations in Excretory System cellular waste still removed by diffusion Protonephridia (NEW) flame cells help regulate solute concentration Evolve in to the nephrons of mammal kidneys First Kidney

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

Asexual reproduction by fission

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

Free-living Flatworms = Class Marine Fresh-water

Classes of Flatworm 1) Free living example = Planaria 2) Flukes parasites in blood & liver swimmers itch 3) Tapeworms

Flukes = Class Parasites of blood and liver

Swimmer’s Itch =Schistosoma

Tape Worms = Class

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