2. Class Trematoda &
3. Class Monogenea:
 Both are parasitic flukes
 Leaf-shaped flatworms
 Endoparasites:
 Live in blood, intestines, lungs, liver, etc.
 Ectoparasites:
 Live on external surfaces of aquatic
hosts
Structure of Flukes
 Anterior & ventral suckers for
attachment to host
 Nervous system like planarian
 Except NO eyespots
 Tegument – outer layer that
protects from host’s immune and
digestive system
Liver fluke
Reproduction of flukes:
 Most are hermaphroditic
 May release 10,000+ eggs at a time!
 Complicated life cycle (p. 692)
Life Cycle:
 Primary host: adult parasite gets
nourishment from this host
 Sexual reproduction
 Intermediate host: larvae derive
nourishment here
 Asexual reproduction
Fluke Diseases in Humans
 Swimmer’s itch: minor skin irritation
and swelling
 Small brown fluke in lakes (in Ohio)
 Dies within skin because humans are not
ideal hosts
 Schistomiasis (blood fluke): disease
that causes tissue damage, bleeding,
tissue decay and possible death
 Lungs, intestine, bladder, & liver
 200 million people affected worldwide
Schistosoma
Animation!
Secondary or
Intermediate host
• snail
Primary host
• human
Swimmer’s itch
4. Class Cestoda
 5,000 species of tapeworms
 Can live in intestines of most
vertebrates
 Enter through undercooked food with
eggs or larvae (cyst)
 Symptoms of infection:




Digestive problems
Weight loss
Lack of energy
anemia
Structure:
 Tegument to protect from host
 Also absorbs nutrients from host
 Scolex: knob-shaped organ with
hooks and suckers to attach to host
 Proglottids: body sections after a
short neck
 Up to 2,000 per tapeworm!
Reproduction:
 Hermaphrodites
 Each proglottid has ovaries and testes
 Filled with 100,000+ eggs each!
 Eggs fertilized by sperm of different
proglottid
Life Cycle:
 Cysts: dormant larvae surrounded by
protective covering in animal muscle