1. Phylum Platyhelminthes
The Worms
Phylum Platyhelminthes
Phylum Nematoda
Phylum Annelida

2. The Worm Characteristics
Bilateral symmetry – the simplest organisms to exhibit this type of symmetry
Invertebrates
Hydrostatic pressure provides structural support

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

5. Phylum Platyhelminthes - Flatworms
Examples:
Tapeworms
Planeria
Parasitic Flukes

6. Phylum Platyhelminthes - Flatworms
Body Structure:
Flattened
Lack segmentation
Acoelomate – no body cavity
˂1 mm to many meters long
Definite head region and body organs
Live in aquatic areas, other organisms

7. Phylum Platyhelminthes - Flatworms
Digestion:
Mouth, Pharynx, digestive tract (no anus)
Incomplete digestive tract
Feed on algae, dead organisms, blood, etc.

9. Phylum Platyhelminthes - Flatworms
Nervous System:
Central nervous system (simplest organism to possess one) – cluster of nerve cells (ganglion) and two nerve cords
Light sensitive eyespots

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

11. 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
Flatworms exchange sperm to fertilize eggs internally
Zygotes are released, attached to weeds, and develop in tiny cocoon
Hatch in 2-3 weeks

14. Phylum Platyhelminthes - Flatworms
Asexual Reproduction:
Fragmentation (Fission)
Regeneration
Can attach to rough substrate and stretch its body into two pieces
Can be cut into and regenerate
Can self-fertilize

15. Phylum Platyhelminthes - Flatworms
Ecological Role:
Food source for dragonflies, water bugs, crustaceans, etc.
Can be parasitic and have oral suckers or hooks to allow them to attach to a host
Symptoms include: headache, fever, joint pain, chronic illness, swelling, tissue damage, etc.
Cleanliness, Good hygiene, eating uncontaminated foods

17. Phylum Nematoda - Roundworms
Classes:
Class Enoplea – Trichina, Whipworm
Class Chromadorea (used to be known as Secernentea) - Hookworm, Ascaris, Pinworm, Heartworm

18. Phylum Nematoda - Roundworms
Examples:
Hookworms
Ascaris
Pinworm
Filarial worms (Heartworms)

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

20. Phylum Nematoda - Roundworms
Digestion:
Complete digestive tract – mouth and anus are located in different locations
Mouth, pharynx (throat), Long gut cavity, no contracting muscles, and an anus
Feed on dead organisms (plants and animals) and the organism in which they live

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

22. Phylum Nematoda - Roundworms
Locomotion:
Thrash to allow contractions
Hydrostatic skeleton uses water for movement

23. Phylum Nematoda - Roundworms
Other Organ Systems:
No respiratory system – breathe through diffusion
No circulatory system
Excretory tubes that transfer waste to anus

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

25. Phylum Nematoda - Roundworms
Ecological Roles:
Important to decomposition and soil nutrition
Feed on bacteria, fungi, protozoans and even other nematodes
Important for nutrient cycling and release of nutrients for plant growth.
Some attack insects, and help to control insect pests.
Some nematodes are reared commercially and released for the control of certain insect pests as a biological insecticide.

26. Phylum Nematoda - Ascaris
Ecological Roles:
Parasitic intestinal worm
Common infection in horses, humans, and pigs
Symptoms: fever, coughing, wheezing, severe abdominal cramps, nausea, and vomiting

27. Phylum Nematoda - Hookworm
Ecological Roles:
Curved head that resembles a hook
Hook to intestines
Causes anemia in patient
Found in soil, burrow through skin, most commonly foot

28. Phylum Nematoda - Pinworm
Ecological Roles:
Most common parasite in the United States
Lives in large intestine
Symptoms: extreme itching, worms in stool (fecal material), pain around rectal area
Easily spread and highly contagious through contact

29. Phylum Nematoda - Trichina
Ecological Roles:
Contracted by eating infected meat
Juveniles enter 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 - Whipworm
Ecological Roles:
Common in U.S. in humans
Intestinal infection
Occurs through contaminated food or unhygienic habits
Symptoms: bloody diarrhea, abdominal pain, anemia, nausea, dehydration, etc.

31. Phylum Nematoda – Filarial Worms
Ecological Roles:
At least 8 species that infect humans
Includes Elephantiasis, river blindness, dog heartworm
Worms live in the lymphatic system
Carried by mosquitoes

32. Phylum Nematoda – Filarial Worms
Elephantiasis:
Fever
Pain in testicles
Enlarged lymph nodes in groin
Massively swollen legs, genitalia, breasts
Swollen liver or spleen

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

36. Phylum Annelida – Segmented Worms
Examples:
Earthworm
Leeches
Bristle Worms

37. 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

38. Phylum Annelida – Segmented Worms
Body Structure:
Some (Polychaetes) have external, paddle-shaped structures (parapodia) with chaetae or bristles
- external gills or appendages

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

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

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

42. 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

43. Phylum Annelida – Segmented Worms
Locomotion:
Muscle contractions allow for movement (both circular and longitudinal)
Setae are hairlike structures that push into the soil for anchoring during movement

44. 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

45. Phylum Annelida – Segmented Worms
Asexual Reproduction:
Regeneration/Fragmentation allows for the earthworm to regenerate the missing part

46. Phylum Annelida – Segmented Worms
Ecological Role:
Food source for organisms such as dragonflies, water bugs, crustaceans, etc.
Parasitic symptoms: headache, fever, joint pain
Stimulates circulation; saliva acts as anesthetic; reduce swelling and clotting