Platyhelminthes

the property of being divisible into symmetrical halves on either side of a unique plane

• def: formation of a head
• free-living, moving animals
• directionality of movement 
• head contacts the environment first
• brain formation to process new info
• location of the mouth

• blastopore becomes the mouth such as an annelid, mollusk, or arthropod
• became the great radiation of invertebrates
• greatest number of species
• nervous system is ventrally located

• blastopore becomes the anus, then a mouth is formed
• became the invertebrate line that led to vertebrates
• largest in size
• nervous system is dorsally located

the opening of the central cavity of an embryo in the early stage of development

of, on, or relating to the underside of an animal or plant; abdominal

of, on, or relating to the upper side or back of an animal, plant, or organ

interaction of 2 different species

both organisms benefit

one organism benefits, the other is unaffected

one organism benefits, the other is harmed

of or relating to parasites that live in the internal organs of animals

any external parasitic organism ex: fleas, leeches, etc

the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis and nerve tissue

congenital condition in which external genitalia and internal sex organs have both male and female characteristics

an organism that supports the immature or nonreproductive forms of a parasite

an organism that supports the adult or sexually reproductive form of a parasite

a free-swimming larval stage in which a parasitic fluke passes from an intermediate host (typically a snail) to another intermediate host or to the final vertebrate host

• blood flukes mature in the veins and reside in the intestines
• main component of transmission is thru fecal matter (where they lay their eggs)
• intermediate host is normally a snail

• ingested by humans thru consumption of raw fish
• adult flukes make babies and lay their eggs in the poo poo
• somehow snails end up comsuming it
• the fish consume the snails and then it goes back to human consumption

An external body covering all parasites share. Non-ciliated. (Syncytial: many nuclei in a single membrane)

extraepidermal layer of one/few multinucleated cell(s) w/ protective covering, in many flukes

Monogenea are a group of largely ectoparasitic members of the flatworm phylum, they clamp onto the gills and external surfaces of fish using a hooked attachment organ called an opisthaptor

the anterior end of a tapeworm, bearing suckers and hooks for attachment to a host

each segment in the strobila of a tapeworm, containing a complete sexually mature reproductive system

• consumption of rare beef by humans
• shelled larva in feces
• grass, contaminated with eggs, is ingested by cows
• cysts in muscle "measly beef"
• undercooked meat with living cysticercus

• bilateral symmetry
• cephalization- formation of a head
• triploblasty: ectoderm, mesoderm, endoderm

• "Turbellaria"- free living flatworms
• Trematoda- endoparasitic flukes
• Monogenea- ectoparasitic flukes
• Cestoda- endoparasitic tapeworms

• free-living
• paraphyletic group
• most are carnivorous
• move by cilia action and muscle contraction
• mouth is located halfway down on ventral side
• marine flatworms are best representatives (bright, contrasting colors, taste bad, sting, release chemical)

• endoparasitic flukes
• digenea is best known group
• complex life cycles: use and intermediate host like a snail and final definitive host is a vertebrate
• inhabit many different regions in the body

• ectoparasitic flukes
• most attach to gills or skin of fish (opisthaptor)
• life cycles--> lost intermediate host

• endoparasitic tapeworms
• scolex
• proglottids
• no intestine
• life cycles--> intermediate host, then definitive vertebrate host