Platyhelminthes

Daniel Jaffe Paige Minteer

Zoey ZoBell

http://images.google.com/imgres?imgurl=http://www.divetrip.com/wakatobi/flatworm02.jpg&imgrefurl=http://www.divetrip.com/phot0410d.htm&usg=__j9-Bk4Alyot44vGWORfQmnPD2gI=&h=480&w=640&sz=123&hl=en&start=2&um=1&itbs=1&tbnid=9H_cUbqZE-qAXM:&tbnh=103&tbnw=137&prev=/images%3Fq%3Dflatworm%26um%3D1%26hl%3Den%26client%3Dsafari%26rls%3Den%26tbs%3Disch:1

Phylum: PlatyhelminthesTurbellaria Dugisea:

Marine, freshwater, predator and scavenger, ciliated body surface

Monogenia Monogians:Marine and freshwater parasites, ciliated bodies, infect outer layer of fish skin.

Trematoda Trematodes and Flukes:Parasites, two suckers attached to host, most life cycles attach to intermediate

Cestoda Tapeworm:Parasites of vertebrates, no head or digestive system, one or more intermediate hosts

Class Examples and Characteristics

Sample AnimalsDugisea Tapeworm

http://gurungeblog.files.wordpress.com/2008/11/platyhelm_turbellaria_dugesia.jpg

http://www.britishbeef.co.uk/tapeworm.gif

Body CavityNo body cavity exists within the

PlatyhelminthesConsidered an Acoelomates, which means

without a cavity

http://biology.unm.edu/ccouncil/Biology_203/Images/SimpleAnimals/Acoelomate.JPG

Body SymmetryPlatyhelminthes exhibit bilateral symmetry,

which means it has one line of symmetry, similar to humans.

A bilateral animal has a dorsal side and a ventral side

A bilateral animal has an anterior end and a posterior end.

http://www.uic.edu/classes/bios/bios100/labs/bilateral.jpg

Nervous SystemCentral Nervous system that processes

information from the eyes and other sensory structures

The bilateral symmetry of this phylum allows for sensory equipment concentrated at the anterior end along with the central nervous system and the brain

This evolutionary tend is known as cephalization

Circulatory SystemNo body or organs for circulationOpen system

http://www.seaslugforum.net/images/flatworm.jpg

Digestive SystemPharynx: a muscular tube in which the mouth

is locatedExtends form ventral sideDigestive juices are sprayed onto pray, and

small pieces are sucked into pharynx, where digestion continues

Undigested wastes are egested through the mouth

Excretory System“Flat” shape in which nitrogenous waste

(ammonia) is removed through diffusion across the body surface.

No organs specialized for gas exchange or circulation. They have a basic structure excretory system is through osmotic balance with their surroundings.

Locomotion/MusculatureMotility a.k.a “Going Dumb”Move by using cilia on their ventral

epidermis, gliding along a film of mucus that they secrete.

Some use muscles to swim through water with an up-and-down form of motion.

http://www.glogster.com/media/2/3/71/6/3710611.jpg

Skeletal TypePlatyhelminthes do NOT contain a skeleton

type.They can literally do the “worm” without

risking any bone fractures.…holy biology!

http://cyberportfolio.st-joseph.qc.ca/classes/carriere/archives/surprised-girl-reading-book.jpg

Sensory Structures/FeaturesGanglia: Located at the anterior end of the

worm, they are dense clusters of nerve cells also known as eye spots

Ventral nerve cords: Coming from the ganglia, a pair of nerve cords that run down the lenth of the body.

Reproduction MethodsSexual and asexual

reproductionRegenerative tissues allow

one split individual to regenerate into two separate worms

Mostly homaphroditeSelf fertilization as well as

cross fertilization is seenDirect development (no larva

stage)http://cas.bellarmine.edu/tietjen/images/Chlonorchis01.gif

Gas ExchangeLack respiratory systemsFlat bodies permits flow of oxygen and

carbon dioxide by diffusion

http://cas.bellarmine.edu/tietjen/images/platyh16.jpg

Unique FeaturesRestricted to living in wet environments

because of the nature of their open gas exchange making them susceptible to dehydration

Their bodies are soft, unsegmented, and resemble ribbons

Some of these species are carnivorous, while the rest are parasitic

Tapeworm disease, or, Cestodiasis is caused by a parasitic type of Platyhelminthes

The End

Thanks for listening!