Phylum Platyhelminthes Flashcards
General facts
Bilateral symmetry Protostome Spiral cleavage Determined cells Triploblastic Cephalization Protonephridia
Cl. Turbellaria
Mostly free living, few parasitic
Most marine
Nerve cords/cerebral ganglia-more centralized
Turbellaria Cephalization
Photoreceptors
Chemoreceptors
Rheoreceptors
Turbellaria Movement
Cilia and muscle
Looping: releaser and adhesive glands
Rhabdite: secrete mucus to glide
Turbellaria Feeding
GVC
One opening for food and waste to filter through
Turbellaria Digestion
Rhabdocoels
Tricladida: extends pharynx further
Polycladida: multiple lobes and farthest extension
Acoel flatworms: no body cavity
Turbellaria Reproduction
Asexual: Transverse fission
Sexual: hypodermic impregnation; penis sparring
Hermaphroditism
Muller’s larva
Invasive species
Bipalium kewense
Hammerhead From Asia via potted plants Feed on earth worms Tetrodotoxin Capping cover sensory structure
Cl. Monogenea
Ectoparasites on fish gills
Ophishaptor: attachment
Cl. Tremetoda
Parasite: Neodermata
Two groups: digenea trematodes and aspidogastrean trematodes
Usually found in digestive systems/livers
Parasite Issues
Need reproduce in definitive host Get eggs out of host New host Get in new host Locate correct environment Stay Anaerobic environment Avoid being digested Avoid killing host
Parasitic body wall
Thicker outer layer for protection called TEGUMENT
Digenean Anatomy
Branches GVC - blind ended - not specialized Oral sucker Maybe not digestive system
Digenean Asexual Reproduction
Egg to miracidium (leaves def. host for intermediate host) amplified germ balls to sporocysts amplified to redia or daughter sporocysts (produce two cercaria) then amplified to cercaria (form lots). Cercaria find definitive host or form a metacercaria if can’t find host (cyst loses tail until right conditions come). Then adult.
Larva Stages
- Miracidium
- Sporocyst
- Redia
- Cercaria
- Metacercaria
Fasciola hepatica
Liver fluke Sheep definitive host Leave and hatch in water Bore into snail (intermediate host) Sporocyst amplified to redia Become cercaria and leave to find sheep by latching onto water veg. to be eaten by sheep
Chinese liver fluke
Human is definitive host
Released in water as feces
Hatch and find snail as intermediate host
Cercariae break out of snail body and attach to fish gills to move into muscle
Infect humans that consume raw fish
Schistosomes
Human is definitive host
Snail is intermediate host
Human release feces in water, find snail, release cercariae, become adults and adults burrow in skin of humans and migrate to intestine
Skip redia stage
Cl. Cestoda: SubCl Cestodaria
Tapeworms Endoparasites: fish and turtles No scolex No segments Hermaphroditic: one testis and one ovaries Muscular proboscis for attach Attachment organs at top and bottom
Cestoda: SubCl. Eucestoda
Anterior scolex
Repeating units: proglottids
True tapeworms
Cestoda: Scolex
Anterior end, ring of hooks Hold fast Buries into intestine wall Rosetella Myzorhynchus
Rosetella
Area at top with hooks
Anterior end
Myzorhynchus
Projection ending forward
Adhesive pads or suckers to hold intestine
Bothria: scolex
Long longitudinal pair of grooves with weak muscular contraction to pinch and hold onto tissue
Bothridia: scolex
4 leaf-like structures off side paired with myzorhynchus to attach
Acetabula: scolex
4 suckers around perimeter of scolex to attach to lining and a rosetellum
Cestoda Scolex: cerebral ganglia
Ganglia creates a ring
Nerve cords run length of creature
Needed to attach
Cestoda Body Wall
Theories: constantly replace integument, block digestive enzymes with other enzymes, alter pH to deactivate attacking enzymes
Collection of fuses cells to create barrier
Cestoda digestion
No system because live in one
Absorb nutrients from host
Cestoda: proglottids-what’s inside?
Excretory canals
Protonephridia
Bladder sac to collect or dump sac and leave hole to excrete
No movement
Master at Reproduction (every proglottid can reproduce)
Cestoda: Reproduction
Immature proglottids don’t have reproduction organs
Mature do reproduce
Simultaneous hermaphrodites
Proglottids come together and mate (1-2 at time)
Break off and leave host to find new host
Cestoda: Mature proglottids
Male: sperm duct, seminal vesicles, cirrus sac, genital atrium
Female: ovary, ootype, seminal receptacle, vagina
Genital atrium is opening to leave; where fertilized
Cestoda: life cycle
Oncosphere: hexacanth larva to be eaten by cow Inverted scolex hatches Human eats undercooked beef Tapeworm attaches to intestine
Tapeworm health problems
Anemia
Lack nutrients
Used to be used to diet
Can be huge
