platyhelminthes, annelida, nematoda

platyhelminthes

bilateral symmetry

triploblastic

acoelomates

cephalization

no C, no R, ladder-like N

turbellarians - planaria

free-living worms

hermaphrodites

auricles

eyespots

circular and longitudinal muscles

auricles

chemosensory structures on the head that can detect chemicals and touch

trematodes - flukes

two hosts: definitive, intermediate

largest group of flatworms

hermaphrodites

complex life cycle

schistosomiasis

trematode life cycle

needing multiple hosts

• hatching into larvae that infects intermediate hosts —> goes to infect definitive hosts

liver fluke

A type of trematode that primarily infects the livers of various mammals, including humans, often causing liver disease.

schistosomiases

blood in the feces or urine caused by penetration from parasitic worms that migrate into the digestive tract

cestodes - tapeworms

scolex

neck

proglottid body form

complex life cycle

scolex

anterior region with modifications to attach to the wall of the host

proglottid body form

series of repeating segments

• each segment contains male and female sex organs

annelida

segmented worms

triploblastic

bilateral symmetry

metamerism

eucolomates

protostomes

closed C, gas exchange R, ventral N

chaetae

small bristles on annelida that help with movement

polychaetaes

largest annelid group

many chaetae on body

parapodia - used to crawl on the sea floor

oligochaetes

no parapodia

fewer chaetae segments

earthworm structure - clitellum, dorsal blood vessel, pharynx

clitellum

secretes mucus to protect the sperm

leeches

two suckers

saliva consists of hirudin anesthetic

nematoda

ubiquitous

abundant

triploblastic

bilateral symmetry

pseudocoelomates

non-segmented

longitudinal muscles only

no C, no R, simple N

hookworms

parasitic nematode

can get infected from larvae formed on grass blades and penetrating the skin

hookworm life cycle

larve penetrates the skin and enters bloodstream

larvae enters spaces and migrates up to the ingestion

eggs pass on in feces

guinea worm

wrapped around a stick and pulled out

first parasitic worm eradicated

trichina worm

from wild boar/bear

produces cysts in the skeletal muscle

filarial worm

a type of parasitic roundworm that causes diseases such as lymphatic filariasis and river blindness, often transmitted by insect vectors.