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Phylum:Platyhelminthes

Parasite Monster Inside Me Part 2

PlatyhelminthesOrigin of the word platyhelminthes: Latin for flatAnimals in this phylum include: tapeworms, planarians,

saltwater flatwormsLevel of organization: -organs and organ systems-Acoelomate (no body cavity)Symmetry: Bilateral (found in most higher organisms)

Basic Platyhelminthes body planThree Germ Layers: First phylum to have all

three1) Ectoderm (outer)2) Endoderm (inner)3)Mesoderm (middle)

Organ Systems

Digestive system: - Three branch system. - Gastrovascular cavity (same as cnidarians) - Gastro = digests food - Vascular = distributes food and gases like the circulatory system

Reproductive System:

Organ SystemsDigestive system: - Three branch system. - Gastrovascular cavity (same as cnidarians)- Gastro = digests food- Vascular = distributes food and gases like the

circulatory system

Reproductive System:- Hermaphrodite (carry both male and female

reproductive organs)

Organ SystemsNervous System: - A ladder-like nerve network extending down from an anterior brain. Head- Anterior Eyespots detect light - Chemosensitive organs at auricles Note: Sensory functions collecting at the anterior end of an organism = Cephalization

Organ SystemsExcretory System:Parts- A web of interconnected tubes that end in flame cells- Flame Cell: Contain beating cilia that create a continuous flow of water

out the excretory pore

Function- Waste moves out of the cells by diffusion and are pushed into the current

created by the flame cells which leads it out of the body through the excretory pore

Platyhelminthes and ParasitismHalf of the flatworm species are parasiticTwo main groups of parasitic flatworms1)Tape worms:- Endoparasite- Adult stage survives in the intestine of a vertebrate hostParts: Scolex: Anterior end equipped with rings of hooks (B) and suckers (A) that hold onto host intestine.Proglottids: Reproductive segments (Carry eggs) released in feces

Platyhelminthes and ParasitismCharacteristics that make tapeworms successful parasites1) Strong outer skin that resists breakdown by hosts digestive enzymes and acids2) Produces millions of eggs per day (only a few will make it to a proper host)

Platyhelminthes and ParasitismFish tapeworm (Diphyllobothrium): - Found off the West coast of Canada and

Alaska (AKA here )- Reaches up to 30ft in length- Found in raw muscle meat of predatory fish

(eg. Salmon, trout)

Tapeworm Lifecycle• Tapeworm lifecycle movie youtube

Tapeworms

Prevention:Freezing meat at -10 C for several days kills the cysts ORCooking the meat thoroughly will kill cystsSymptoms:- Usually asymptomatic (4/5 cases)- Weight loss- Abdominal pain- Diarrhea- Vomiting- Fatigue

Platyhelminthes and ParasitismTwo main groups of parasitic flatworms2) Flukes:- Endoparasite- Adult stage survives in the intestine of a vertebrate hostParts:- Oval shaped body similar to free living planaria with a reduced digestive and nervous systemTypes:Named after the organ they infect- Liver fluke- Lung fluke- Blood fluke

Assignment

• Crossword• Vocab 628-629