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Presentation on theme: "WORMS."— Presentation transcript:


2 Flatworms: Phylum Platyhelminthes
Soft and Flat Tissues and Internal Organ Systems 3 embryonic germ layers (Ecto, Meso, & Endoderm) Bilateral symmetry Cephalization Acoelomates-without coelom (no fluid-filled body cavity)


4 Feeding Carnivore Scavenger Parasitic Mouth/anus with pharynx (muscular tube that moves food and waste) Gastrovascular cavity – digestion/absorption Parasites – simple or no digestive system b/c feed on blood, tissue fluids, or cell pieces of host

5 Respiration, Circulation, Excretion
Diffusion (transport O2 and nutrients) through body walls Flame cells – remove excess water and waste Connected to pores in the skin

6 Response Ganglia – controls N.S. (nerve cell cluster)
Eyespot – detects light changes Some have specialized cells to detect chemicals, food, etc.


8 Movement Cilia on epidermal cells for gliding
Muscle cells for twisting/turning

9 Reproduction Hermaphrodites
Sexual by 2 worms joining, exchanging sperm, and each lay eggs Internal fertilization Asexual by fission (organism splits in 2 and each half grows new parts)

10 Figure 27–3 The Anatomy of a Flatworm
Ganglia Eyespot Freshwater flatworms have simple ganglia and nerve cords that run the length of the body. The excretory system consists of a network of tubules connected to flame cells that remove excess water and cell wastes. Head Nerve cords Gastrovascular cavity Flatworms use a pharynx to suck food into the gastrovascular cavity. Digested food diffuses from the cavity into other cells of the body. Eyespots in some species detect light. Excretory system Ovary Testes Mouth Pharynx Most flatworms are hermaphrodites, having male reproductive organs (testes) and female reproductive organs (ovaries) in the same organism. Flame cell Excretory tubule

11 Turbellarians Flukes Tapeworms Classes of Flatworms:


13 Class Turbellaria: Turbellarians
Free-living Marine or fresh water Not Parasitic

14 Ex. Pseudobiceros gloriosus
Tropical free-living flatworm (non-parasitic)

15 Ex. Planaria Cross-eyed; fresh water free-living flatworm (non-parasitic)

16 Class Trematoda: Flukes
Parasitic Infect internal organs of hosts Blood flukes – travel to intestines of host Some have Multiple Hosts

17 Ex. Blood Fluke (not free-living)
Parasite that matures in human blood vessels

18 Schistosoma mansoni (has multiple hosts: Snail=intermediate host
Human=primary host)

19 Figure 27-5 Primary host (human) Flukes mature and reproduce sexually in the blood vessels of human intestines. Embryos are released and passed out with feces. Intermediate host (snail) Adult fluke Human intestine Embryo Ciliated larva Tailed larva After asexual reproduction, new larvae are released from the snail into the water. They then infect humans, the primary host, by boring through their skin. Once in the water, embryos develop into swimming larvae that infect an intermediate host (snail).

20 Class Cestoda: Tapeworms
Parasitic Lives in intestines Long and flat Scolex-head with suckers or hooks Proglottids-body segments

21 Cow/Fish (intermediate host) consumes food or water w/ zygotes.
Hatch to larvae and burrow into muscles as cysts (protected) human eats meat not fully cooked and larvae activated to grow to adult in human intestines.

22 Roundworms: Phylum Nematoda
Unsegmented Most are free-living Digestive tract with two openings – mouth and anus Pseudocoelom-false body cavity

23 Feeding Most are carnivores Use mouth parts and spines to catch food
Hook Worms

24 Respiration, Circulation, Excretion
Diffusion through body walls

25 Response Simple nervous system
Nerves run body length from Ganglia in head Simple sense organs to detect chemicals from prey or hosts

26 Movement Hydrostatic skeleton
Muscles and fluid in the pseudocoelom work together to produce movement

27 Reproduction Sexual Internal fertilization Separate genders

28 Human Disease --Parasitic Roundworms
Trichinosis-Causing Worms Filarial Worms Ascarid Worms Hookworms

29 Trichinella  Trichinosis
Cysts are ingested from eating animal muscle tissue Females burrow into intestinal wall Larvae travel to organs via bloodstream and form cysts

30 Filarial Worms Live in blood and lymph vessels
Transmitted by mosquitoes Can block the movement of fluids Elephantiasis

31 Ascaris 1. Eggs hatch in intestines
2. Larvae burrow into bloodstream to lungs 3. Travel to air passages, then swallowed 4. Carried to the intestines and mature 5. Eggs released via feces Spread by eating improperly washed vegetables (foods)


33 Hookworms ¼ of the human population infected with hookworms
Eggs hatch outside body and develop in soil Use sharp toothlike plates and hooks to burrow into skin and enter bloodstream Travel to lungs and then intestines Suck blood causing weakness Don’t walk barefoot outside!!!


35 Annelids: Phylum Annelida
--Segmented worms with a coelom (body cavity) that is lined with mesoderm

36 Feeding and digestion Filter feeders to predators Earthworm
Full Digestive Tract: mouth  pharynx  esophagus  crop  gizzard  intestine  anus Crop- store food Gizzard- grind food

37 Circulation Closed system, 2 major blood vessels
Dorsal blood vessel: tail  head (pumps like heart) Ventral blood vessel: head  tail

38 Respiration and Excretion
Skin (moist due to mucus secretion) - land Gills - aquatic Excretion- Nephridia - filter out fluid/liquid waste Anus – solid waste

39 Movement- Reproduction- Hydrostatic skeleton
Longitudinal muscles – short and fat Circular muscles – long and thin Setae- brush hair-like projections Reproduction- Mostly sexual, some hermaphrodites, some separate sexes Clitellum-thick band secretes mucus ring after 2 worms exchange sperm for fertilization Mucus ring slips off and forms protective cocoonhatching


41 Classes of Annelids

42 Class Oligochaeta: Oligochaetes- Earthworms
Few setae on each segment Soil or fresh water

43 Class Hirudinea: Leeches
External parasites Suck blood and body fluids of host Medicinal Uses Reduces swelling and prevents clotting

44 Class Polychaeta: Polychaetes
Sandworms, bloodworms Marine Paired paddle-like appendages w/ setae Live in coral reefs, sand, mud

45 What do you think caused this marking?
Worm? Bacteria? Virus? Fungus? Hickey?

46 Ringworm Not caused by a worm! Fungal infection
Can occur on any part of body Contact with infected people, animals, soil, etc. Medically called Tinea

47 Earthworm Dissection

48 External View

49 Internal Structure

50 Pharynx

51 Aortic Arches

52 Seminal Vesicle

53 Seminal Receptacle

54 Septum

55 Crop

56 Gizzard

57 Intestine

58 Ventral Nerve Cord

59 Dorsal Blood Vessel

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