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The Worms

This article provides an overview of the characteristics, examples, and ecological role of the worms. It covers the phyla Platyhelminthes and Nematoda, including their body structure, digestion, nervous system, locomotion, reproduction, and ecological roles. The article also highlights common examples of flatworms and roundworms.

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The Worms

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  1. The Worms Phylum Platyhelminthes Phylum Nematoda Phylum Annelida

  2. Choanoflagellates

  3. The Worm Characteristics • Bilateral symmetry – the simplest organisms to exhibit this type of symmetry • Invertebrates – use hydrostatic pressure to provide structural support (made of water). • Made of the three germ layers: endoderm, ectoderm, and mesoderm. • Undergo cephalization

  4. Choanoflagellates

  5. Phylum Platyhelminthes - Flatworms Classes: • Class Cestoda - Tapeworms • Class Turbellaria - Planeria • Class Trematoda – Flukes

  6. Phylum Platyhelminthes - Flatworms Examples: • Tapeworms • Planeria • Marine Flukes

  7. Phylum Platyhelminthes - Flatworms Body Structure: • Flat • Lack segmentation • Acoelomate – no body cavity • ˂1 mm to many meters long • Definite head region • Live in aquatic environments or in/on other organisms

  8. Phylum Platyhelminthes - Flatworms Digestion: • Mouth, Pharynx, digestive tract • Incompletedigestive tract which means no anus • Feed on algae, dead organisms, blood, etc.

  9. Label Your Flat Worm Diagram

  10. Phylum Platyhelminthes - Flatworms Nervous System: • Central nervous system (simplest organism to possess one) – cluster of nerve ganglia that form a brain and two nerve cords • Light sensitive eyespots which are examples ofphotoreceptors. • Label Your Flatworm Diagram

  11. Phylum Platyhelminthes - Flatworms Locomotion: • Contracting longitudinal muscles • Cilia on underside • Mucous lubricates organism to allow it to glide

  12. Phylum Platyhelminthes - Flatworms Other Organ Systems: • Contains no true organs • No respiratory system • No excretory system • Absorption of oxygen occurs through diffusion

  13. Phylum Platyhelminthes - Flatworms Sexual Reproduction: • Almost always hermaphroditic (monoecious) • Flatworms can exchangesperm to fertilize eggs internally • Zygotes are released, attached to weeds, and develop in cocoons • Hatch in 2-3 weeks

  14. Phylum Platyhelminthes - Flatworms Asexual Reproduction: • Fragmentation • Regeneration • Can attach to rough substrate and stretch its body into two pieces • Can be cut in two and regenerate • Can self-fertilize if needed but prefer not to

  15. Phylum Platyhelminthes - Flatworms Ecological Role: • Parasitic: have oral suckers/hooks to allow them to attach to a host • Symptoms include: headache, fever, diarrhea, difficulty breathing, extreme weightloss, abdominal pain, palpitations, swelling, tissue damage, etc. • How to prevent contraction: cleanliness, good hygiene, eating uncontaminated foods, cook foods thoroughly

  16. Choanoflagellates

  17. Phylum Nematoda - Roundworms Classes: • Class Enoplea – Trichina, Whipworm • Class Chromadorea - Hookworm, Ascaris, Pinworm, Heartworm

  18. Phylum Nematoda - Roundworms Body Structure: • Round • Lack segmentation • Psuedocoelomate – false body cavity • No circular muscles • Longitudinal muscles only (lengthwise down body) • Aquatic environments and other organisms

  19. Phylum Nematoda - Roundworms Digestion: • Completedigestive tract – mouth and anus are located in different locations • Have a mouth, a pharynx (throat), a long gut cavity, and an anus • Feed on dead organisms (plants and animals) and take nutrients from the organism in which they live

  20. Phylum Nematoda - Roundworms Nervous System: • Two nerves cords (dorsal and ventral) • Branch toward ganglia (the brain)

  21. Phylum Nematoda - Roundworms Locomotion (movement): • Thrash to allow contractions • Hydrostatic skeleton uses water for movement

  22. Phylum Nematoda - Roundworms Other Organ Systems: • No respiratory system – breathe through diffusion • No circulatory system • Excretory tubesthat transfer waste to anus

  23. Phylum Nematoda - Roundworms Sexual Reproduction: • Females produce eggs • Males produce sperm • Internal fertilization • Eggs are laid • Some hatch outside • Some hatch in host

  24. Phylum Nematoda - Roundworms Ecological Roles: • Helps with decomposition • Add nutrients to the soil which is good for plants • Some attack insects, and help with insect population • Some nematodes are bred commercially and released for the control of certain insect pests as a biological insecticide.

  25. Phylum Nematoda – Loa Loa • African eye worm that means “worm worm” • Thought by some to be harmless. • Contracted by the bite of a deer fly or a mango fly

  26. Phylum Nematoda - Ascaris • Parasitic intestinal worm • Symptoms: fever, nausea, coughing, gagging, shortness of breath, abdominal cramps, vomiting, malnutrition, and death • Contracted by contaminated soils (barefoot/play) or uncooked foods; also, from person to person

  27. Phylum Nematoda - Hookworm • Intestinal (small intestine) parasite • Curved head that resembles a hook • Symptoms same as previous along with anemia and heart failure • Found in contaminated soils; burrows through skin, most commonly foot

  28. Phylum Nematoda - Pinworm • Most common parasite in the United States • Lives in large intestine • Symptoms: extreme itching, worms in stool (feces), pain around rectum • Easily spread and highly contagious through contact • Medicines found over-the-counter

  29. Phylum Nematoda - Trichina • Contracted by eating infected pork • Enters blood vessels and lymph nodes and are carried to muscles • Symptoms: fever, swelling of face and eyes, and serious muscle pain • Neck, chest, and limbs can swell if treatment is not sought

  30. Phylum Nematoda – Filarial Worms Elephantiasis: • Mosquito bites only • Causes a blockage of the lymphatic system (fluid builds up) • Enlargement of infected area (usually limbs or external genitalia) • Skin becomes dry, thick and pebbly • Fever, chills, extreme swelling

  31. Phylum Nematoda – Filarial Worms Heartworms: • The larvae enter the heart through the blood stream where they grow and reproduce until they clog the heart of their host and kill it. • Lethargy, cough, difficulty breathing, heart failure • Video

  32. Choanoflagellates

  33. Phylum Annelida – Segmented Worms Examples: • Class Oligochaeta - Earthworm • Class Hirudinea - Leeches • Class Polychaetes - Bristle Worms

  34. Phylum Annelida – Segmented Worms Examples: • Earthworm • Leeches • Bristle Worms

  35. Phylum Annelida – Segmented Worms Body Structure: • Body divided into ring-like segments • Coelomate (has a true body cavity) • Look like a stack of donuts • Have circular muscles • Have longitudinal muscles

  36. Phylum Annelida – Segmented Worms Body Structure: • Some worms, like polychaetes, have external, paddle-shaped structures called parapodia (leg-like structures) with chaetae or bristles • These polychaetes are aquatic and have external gills

  37. Phylum Annelida – Segmented Worms Digestion: • Complete digestive tract –mouth and anus located at different locations • Mouth, Pharynx, Esophagus, Crop, Gizzard, Intestine, and Anus

  38. Phylum Annelida – Segmented Worms Circulatory System: • Closed circulatory system (10 aortic arches -5 pairs) • Oxygen is pumped throughout the body through the blood vessels

  39. Phylum Annelida – Segmented Worms Respiration and Excretion: • Breathe through their skin though some have gills • Nephridia (kidneys) found in every segment to get rid of waste

  40. Phylum Annelida – Segmented Worms Nervous System: • Has two structures that form the brain ganglia • The ventral and dorsal nerves extend down the body • Photoreceptors that detect light • Detect vibrations easily

  41. Phylum Annelida – Segmented Worms Locomotion (movement): • Muscle contractions allow for movement (both circular and longitudinal) • Setaeare hair-like structures that push into the soil for anchoring during movement

  42. Phylum Annelida – Segmented Worms Sexual Reproduction: • Some are hermaphroditic • Can receive sperm from other worms via the clitella • The clitella produces a cocoon from which fertilized eggs hatch

  43. Phylum Annelida – Segmented Worms Asexual Reproduction: • Fragmentation and regeneration allows for the earthworm to regenerate the missing part

  44. Phylum Annelida – Segmented Worms Ecological Role: • Leeches stimulate circulation; saliva has an anticoagulant which causes free bleeding; treatment reduce swelling and prevents clotting

  45. You Need To know This!!!

  46. Phylum Platyhelminthes, Nematoda, & Annelida • Phylum Platyhelminthes • Flattened • Acoelomate • Genital Pore • Pharynx • Ganglion • Eyespots • Longitudinal Muscles • Cilia • Segmented • Coelomate • Parapodia • Chaetae • Internal Fertilization • Fragmentation • Regeneration • Phylum Nematoda • Rounded • Pseudocoelomates • Circular Muscles • Parasitic • Phylum Annelida • Aortic Arches • Nephridia • Setae • Clitellum

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