ZOO 115 Invertebrate Zoology - PowerPoint PPT Presentation

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ZOO 115 Invertebrate Zoology

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ZOO 115 Invertebrate Zoology Platyhelminthes Parasites – PowerPoint PPT presentation

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Title: ZOO 115 Invertebrate Zoology


1
ZOO 115 Invertebrate Zoology
  • Platyhelminthes
  • Parasites

2
Parasitism - Adaptations
  • Method of attachment
  • SUCKERS - Trematoda and Monogea

3
Parasitism - Adaptations
  • Getting into host
  • Penetration special glands to digest skin
  • Getting into host
  • Passive eaten by host
  • Need outer resistant covering
  • Living tegument
  • Permeable to H20, amino acids, sugars
  • Tolerate great changes in pH.

4
Parasitism - Adaptations
  • Osmotic Pressure
  • Must be lower than surroundings why?
  • Facultative anaerobic respiration
  • 4X more efficient than in vertebrates
  • Reduced structures
  • Sensory (except chemo)
  • Muscles
  • Nervous system
  • Digestive tract

5
Parasitism - Adaptations
  • Increased reproduction
  • Produce many many eggs
  • e.g. Fish tapeworm 2 million eggs/day and can
    live for 15 yrs (100 trillion eggs in lifetime)
  • Polyembryony many young from one egg.
  • Asexual stages amplify numbers
  • e.g. Fasciola hepatica produces 500,000 eggs in a
    lifetime that produce 42 trillion offspring.

6
Parasitism - Adaptations
  • Host reactions to parasites
  • Susceptibility varies with life cycle and health
    of host
  • Single host parasite usually becomes more
    commensal
  • Castration
  • Multiple hosts parasite can kill the host
  • Snails
  • Ants
  • Internal parasites develop ways of hiding from
    immune system

7
Parasitism - Adaptations
  • Host specificity varies
  • Some are completely specific to their hosts
  • Problems with non-specificity
  • Swimmers itch
  • Nematode and encephalitis

8
Class - Trematoda
  • Common Name - Flukes
  • Common parasites of all major vertebrate taxa.
  • gt11,000 species

9
Class Trematoda - General Anatomy of Adult
  • Suckers for feeding and attachment
  • Non-cliated tegument
  • Protection against enyzmes,
  • Gas exchange
  • Eliminate nitrogenous waste
  • Absorb glucose and amino acids

10
Class Trematoda - General Anatomy of Adult
11
Class Trematoda Life Cycles
  • Chinese Liver Fluke (Opisthorchis or Clonorchis)
  • Infests 20 million E. Asians
  • Adult 2.5 cm in length
  • Live 8 yrs
  • Produce 4000 eggs per day for 6 mo
  • Symptoms Jaundice, gallstones, debilitation and
    liver cancer

12
Class Trematoda - Life Cycle
13
Class Trematoda Life Cycles
  • Blood Fluke (Schistosoma sp)
  • Dioecious Male 6-10 mm, Female much smaller
    (fits into groove in male)
  • Develop cercaria directly from sporocyst (no
    redia)

14
Class Trematoda - Reproduction
  • Why is amplification important?
  • What impact might the multiple host strategy of
    the parasite have on the hosts?

15
Class Monogenea
  • Ectoparasites only one host
  • Mostly infest fishes
  • Adults have suckers and hooks
  • Larvae hooked free-swimming (oncomiradium)

16
Class Monogenea life cycles
  • Dactylogyrus sp.
  • More eggs with increasing temperature
  • Eggs released sit on bottom
  • Hatch into swimming larvae
  • On contact with fish metamorphose into adult form

17
Class Monogenea life cycles
  • Polystoma sp.
  • Eggs stay in frog until frog gets in water
  • Hatch into swimming larvae
  • Larvae attach to gills of tadpoles
  • Tadpoles metamorphose and larvae crawls over
    belly and goes into bladder

18
Class Cestoda
  • Common name Tapeworms
  • 3400 species
  • Gut is absent specialized neodermis for
    nutrient uptake.
  • Live about 15-20 yrs
  • Can copulate

19
Class Cestoda - Anatomy
  • Can reach 15 m in length!
  • Head region
  • Attach to preys intestinal tract

20
Class Cestoda - Anatomy
  • Proglottids
  • Each is a complete hermaphroditic reproductive
    system
  • Both Cross and Self-Fertilization

21
Class Cestoda Life Cycles
22
Class Cestoda Life Cycles
  • If eggs go in water
  • swimming larvae (onchosphere) hatches within 10
    days
  • Eaten by copepods
  • Copepods eaten by fish
  • Penetrates gut, migrates to muscle and
    transformed into dormant miniaturized adult
  • Eaten by warm-blooded host

23
Class Cestoda Life Cycles
  • If eggs go on land
  • Eggs eaten by cattle
  • Onchosphere larvae hatch, bore into intestinal
    wall and transported through circulatory system
    to muscle tissue
  • Develops into bladderworm larvae (Cysticercus).
  • Eaten by warm-blooded host.

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24
Class Cestoda
  • Causes Diarrhea, Weight loss and inflammation
  • Biggest problem is accidental infestations
  • Bladder worm will develop into tissue other than
    muscle.
  • Cyst can contain liters of fluid which could
    cause severe infection if released
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