Platy-helminthes and Nematoda

1. Platy-helminthes andNematoda

2. Common Name Platy-helminthes Nematoda Roundworm • Flatworm Tapeworm pinworm Planaria Fluke

3. Symmetry Platy-helminthes Nematoda Bilateral • Bilateral

4. Platy-helminthes and Nematoda • Tissue Complexity: eumetazoa (all animals except the sponges, placozoans and mesozoans) • Germ Layers: 3

6. Feeding/ Digestion Platy-helminthes Nematoda Complete digestive tract • Gastrovascular cavity

7. Respiration, Circulation, Excretion Platyhelminthes Nematoda Respiration: Diffusion Circulation: Diffusion Excretion: Nephridia. • Respiration: diffusion • Circulation: Diffusion • Excretion: Flame cells (nephridia)

8. Response, Movement, Reproduction Platyhelminthes Nematoda Response: Simple, ganglia. Movement: Hydrostatic skeleton. Reproduction: Hermaphroditic. External and internal fertilization. • Response: Simple, ganglia and 2 eyespots. • Movement: Hydrostatic skeleton. • Reproduction: Hermaphroditic. External and internal fertilization.

10. Other Unique Characteristics Platyhelminthes Nematoda Parasitic (must be inside host to reproduce) • No digestive tract • Advanced reproduction (penis fencing)

11. Big Idea 1: The Process of Evolution Similarities Differences To complex organisms: Feeding/digestion: gastrovascular cavity and complete digestive tract Respiration: diffusion Circulation: diffusion Excretion: flame cells and nephridia Response: Ganglia • To complex organisms: • Symmetry: bilateral • Tissue complexity: eumetazoa • Germ Layers: 3 • Gut openings: 2 • To bacteria: • Respiration: diffusion • Circulation: diffusion

12. Evolutionary Characteristics • Lowest organism with a head, centralized nervous system, complex reproductive organs, mesoderm, and a bilaterally symmetrical body

13. Big Idea 2: Biological systems Efficient resource gathering Efficient conservation of energy Platy-helminthes One cell thick epidermis Thin body allows for minimal energy expenditure Nematoda Parasitic, do not need to go far to obtain nutrients Breathe through skin, no respiratory system taking up space and expending energy • Platy-helminthes • Absorb digested material directly through diffusion • Thin bodies allow for waste to diffuse out of the skin • Nematoda • Most are parasitic, obtain nutrients by burrowing into the intestine or lungs of animals

14. Innate Behavior Platyhelminthes Nematoda Ganglia allow response to light, heat and touch Some studies show they have chemoreceptive pores, allowing response to chemical signals Seek out hosts in which to feed and reproduce • Have eyespots, allowing them to respond to changes in light • Predatorial-use pharynx opening to suck food particles into gastrovascular opening • Innately feed on blood and tissues of host

15. Learned Behavior Platyhelminthes Nematoda While nematodes have been shown to respond to chemical and tactile stimuli, all research has been inconclusive in showing any memory of stimuli • Have been shown to respond to classical conditioning (an experiment involving associating bright light with an electric shock led to flatworms responding to light as if being electrocuted) • Offspring and worms that were fed crushed 1st generation worms also displayed this learned reaction, indicating chemical memory

16. Cooperative Behavior Platyhelminthes Nematoda Hunt in groups Gather in groups and feed Gene causing this is related to the Neuropeptide Y receptor gene in humans Mating is through touch Textile signal • Trematode flatworm parasites exist in cooperative colonies consisting of big reproducers, which release hundreds to thousands of clonal offspring daily, and specialized soldiers that defend the colony.

17. Platy-helminthes Big Idea 4: Biological Systems Interact ~ in the environment • Investigation of polyclad chemical defense mechanisms revealed that several polyclads contain strong toxins such as tetrodotoxin. These findings suggest that flatworms are warning of their unpalatability and that their visual predators, fish, will quickly learn to avoid them by recognition of their distinct and bright colour pattern. Experiments performed by Hing P. Ang and Leslie J. Newman provide the first experimental evidence of aposematiccolouration in pseudocerotid flatworms. • Trematodes usually have a pair of suckers for crawling and clinging to the host's tissue • restricted to living in a wet environment, such as in freshwater, sea or in moist terrestrial environmen • Some flatworms have primitive light-sensing "eyes" that allow them to move either towards or away from light, while other species have different types of sensors on their bodies, including chemical, balance, and water movement receptors

18. Nematoda (Big Idea 4 cont.) • They are found in almost every imaginable habitat , including terrestrial (land-based), freshwater, and saltwater ecosystems , as well as within other organisms as parasites. • Nematodes can be herbivorous, carnivorous, or parasitic, and include both generalists (who make use of a wide variety of resources) and specialists (who make use of only particular resources)

19. Big Idea 4: Biological Systems Interact ~ Role in environment Nematoda Platy-helminthes • decomposition and nutrient cycling, where they are often the intermediate decomposers that partly break down organic materials so that they can then be dealt with by bacterial decomposers • parasitic or commensal relationships with plants and animals • addaptations that allow for certain host environments allow the parasitic organisms to thrive