Nicole CostaNicole Costa

Platyhelminthes

Introducing…our lovely Platy!Introducing…our lovely Platy! Platy are…flatworms! Platy are…flatworms! (+20,000 species!)(+20,000 species!) They are:They are:

bilaterally symmetrical triploblastic (have 3 main cell layers) layers) Cephalization (head & sensory organs developed, Cephalization (head & sensory organs developed,

has brain, nerve fibers) & muscle layershas brain, nerve fibers) & muscle layers without a body cavity (coelom) besides the gut without a body cavity (coelom) besides the gut

(though Acoela, Cestoda, & some smallest ones lack it)(though Acoela, Cestoda, & some smallest ones lack it) & No anus & No anus Sac-like body with one opening (pharynx)Sac-like body with one opening (pharynx) b/c lack any other cavity, some are polycladids (gut b/c lack any other cavity, some are polycladids (gut

extremely branch to transport food everywhere)extremely branch to transport food everywhere) Lack s other cavities= respire via skin diffusion= flatLack s other cavities= respire via skin diffusion= flat

3 main types of Platy:3 main types of Platy: Turbellaria (most are free-living forms, includes

planarians—biology’s experimental friend) Trematoda, flukes (internal & external parasites) Cestoda, tapeworms (intestinal vertebrate

parasites)

TurbellariaTurbellaria : : oceans, fresh water, and moist terrestrial oceans, fresh water, and moist terrestrial

habitatshabitats a few are parasitic a few are parasitic

Trematoda: Trematoda: (see parasites)(see parasites)

Cresoda: Cresoda: (see parasites, most specifically intestines)(see parasites, most specifically intestines)

Parasites:Parasites: INSIDE OF YOU & other organisms!INSIDE OF YOU & other organisms!

Mollusks (trematode larvae irritate & sometimes Mollusks (trematode larvae irritate & sometimes become natural pearls)become natural pearls)

Snails, fish, rodents, pigs, cattle, otherSnails, fish, rodents, pigs, cattle, other Humans (~200 million)Humans (~200 million)

FecesFeces

Platy are found…Platy are found…

Tapeworm can grow & consume more of host than food

Platy Favorite Activities are…Platy Favorite Activities are… Believed 1Believed 1stst to move forward & search/hunt for food & mates to move forward & search/hunt for food & mates

Carnivores, scavengers,Carnivores, scavengers, Like to mateLike to mate

Believed flatworm-like animals 1Believed flatworm-like animals 1stst to have head, brain, paired senses & a tail to have head, brain, paired senses & a tail =1=1stst to control movement/direction of where they are going to control movement/direction of where they are going

Exception—Parasites:Exception—Parasites: Use intermediate hosts to transport species between definitive hosts Attach to hosts’ intestinal wall with hooks or suckers & absorb nutrients Mating

Platy UniquenessPlaty Uniqueness BilateralBilateral Turbellaria:Turbellaria:

Mesoderm layer with muscles Mesoderm layer with muscles Fluid in body cavity as hydrostatic skeleton (waste & gametes collected &/or primitive circulatory Fluid in body cavity as hydrostatic skeleton (waste & gametes collected &/or primitive circulatory

system)system) Coordinate cilia to glide on secreted mucus trail, though some swim via muscle contractionsCoordinate cilia to glide on secreted mucus trail, though some swim via muscle contractions

Flame cell systemFlame cell system Cells w/ cilia that control excretion & osmotic regulation in freshwater Cells w/ cilia that control excretion & osmotic regulation in freshwater

(Adult) Parasites:(Adult) Parasites: Loss of cephalization & sensory organs—replaced by hooks & suckers to attach to the

host intestine Extensive development of reproductive system Lack of developed nervous system & gastrovascular system Development of tegument (protection from digestive juices)

Genealogy: Platy super-nessGenealogy: Platy super-ness Platyzoas clade Platy may even be Platy may even be polyphyleticpolyphyletic (from 2 (from 2 independent ancestors)independent ancestors)

most could be from most could be from Lophotrochozoa (molluscs & Lophotrochozoa (molluscs & earthworms group)earthworms group)

rest near the base of animal rest near the base of animal diversity diversity

Gave bilateral symmetry Gave bilateral symmetry ((Bilateria)

Differ from our ancestors in lack Differ from our ancestors in lack of body cavity (of body cavity (Acoelomates)

Seeking perfect host mate…Seeking perfect host mate…

Unselfish mate—one I can get right into & Unselfish mate—one I can get right into & squirm about afterwards & lay my eggs in squirm about afterwards & lay my eggs in

Prefer vertebrates maybe a:Prefer vertebrates maybe a: Fish—a comfortable & rather familiar presenceFish—a comfortable & rather familiar presence Land dweller, human—some believe we have lots Land dweller, human—some believe we have lots

in common as parasites; has excess energy to eat; in common as parasites; has excess energy to eat; if DNA could be combined it would be divine to if DNA could be combined it would be divine to have greater intelligence offspring & be able to have greater intelligence offspring & be able to survive without a host, though we still dig around survive without a host, though we still dig around another’s insides (do not have to starve and look another’s insides (do not have to starve and look for food or shelter after getting in)for food or shelter after getting in)

human + platyhelminthes= giant flat creature with human + platyhelminthes= giant flat creature with legs, head (with intelligence) and ability to think; can legs, head (with intelligence) and ability to think; can go inside other creatures & live off their energy, lay go inside other creatures & live off their energy, lay eggs, and leave via the anus; eats and expels waste eggs, and leave via the anus; eats and expels waste from the same opening; very good at moving from the same opening; very good at moving forward, mating, & huntingforward, mating, & hunting

HostsHosts

http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html http://animaldiversity.ummz.umich.edu/site/accounts/information/Platyhelmin

thes.html http://cas.bellarmine.edu/tietjen/images/platyhelminthes.htm http://www.pbs.org/kcet/shapeoflife/animals/platyhelminthes.html http://www.pbs.org/kcet/shapeoflife/episodes/hunter.html http://biology.unm.edu/ccouncil/Biology_203/Summaries/SimpleAnimals.htm http://planet.uwc.ac.za/nisl/biodiversity/Chapter2/page_20.htm http://www.starfish.ch/c-invertebrates/flatworms.html http://www.emc.maricopa.edu/faculty/farabee/BIOBK/

BioBookDiversity_7.html http://en.wikipedia.org/wiki/Platyzoa