Title: ZOO 115 Invertebrate Zoology
1ZOO 115 Invertebrate Zoology
- Platyhelminthes
- Parasites
2Parasitism - Adaptations
- Method of attachment
- SUCKERS - Trematoda and Monogea
3Parasitism - 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.
4Parasitism - 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
5Parasitism - 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.
6Parasitism - 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
7Parasitism - Adaptations
- Host specificity varies
- Some are completely specific to their hosts
- Problems with non-specificity
- Swimmers itch
- Nematode and encephalitis
8Class - Trematoda
- Common Name - Flukes
- Common parasites of all major vertebrate taxa.
- gt11,000 species
9Class 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
10Class Trematoda - General Anatomy of Adult
11Class 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
12Class Trematoda - Life Cycle
13Class 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)
14Class Trematoda - Reproduction
- Why is amplification important?
- What impact might the multiple host strategy of
the parasite have on the hosts?
15Class Monogenea
- Ectoparasites only one host
- Mostly infest fishes
- Adults have suckers and hooks
- Larvae hooked free-swimming (oncomiradium)
16Class 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
17Class 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
18Class Cestoda
- Common name Tapeworms
- 3400 species
- Gut is absent specialized neodermis for
nutrient uptake. - Live about 15-20 yrs
- Can copulate
19Class Cestoda - Anatomy
- Can reach 15 m in length!
- Head region
- Attach to preys intestinal tract
20Class Cestoda - Anatomy
- Proglottids
- Each is a complete hermaphroditic reproductive
system - Both Cross and Self-Fertilization
21Class Cestoda Life Cycles
22Class 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
23Class 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.
http//sps.k12.ar.us/massengale/tapeworm.gif
24Class 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