Slide 1

PLATYHELMINTHES Slide 2 Characteristics Flatworms Class Trematoda: Tapeworms Class Cestoda: Flukes Class Turbellaria: Planarians Bilateral symmetry Many are parasites Size 1mm to 1 M Slide 3 Anatomy Long narrow body No legs Acoelomates Epidermis cells make up skin No circulatory system Slide 4 Anatomy Takes in oxygen but no formal respiratory system First phylum with muscles No skeleton Simplest organisms with a brain Two simple nerve cords and two brains are small bundles of nerves Slide 5 Feeding Planarians are scavengers Tapeworms and flukes are all parasites Flatworms feed through tube-like mouth. Digestive juices flow out to start digestion, worm sucks up partially digested food Slide 6 Reproduction Asexual reproduction: Regeneration (like in planarians) Sexual Reproduction: Flatworms are hermaphrodites Produce both eggs and sperm. Exchange sperm with other worms Slide 7 Habitat Free-living: Ocean Freshwater Moist soil Parasites: On or in host organism What are some biotic and abiotic factors? Slide 8 Adaptations Parasites live off host organism, but rarely kill the host Why? Adults produce a lot of eggs and sperm Liver flukes have multiple hosts. Why do you think this is advantageous? Do you eat sushi?