Upload
allison-randall
View
235
Download
5
Tags:
Embed Size (px)
Citation preview
14-1
CHAPTER 14 CHAPTER 14 CHAPTER 14 CHAPTER 14
Flat Worms:Flat Worms:Phylum PlatyhelminthesPhylum Platyhelminthes
Flat Worms:Flat Worms:Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-2
General FeaturesGeneral Features
Animals that actively seek food, shelter, Animals that actively seek food, shelter,
home sites, and mates require a different set home sites, and mates require a different set of strategies and body organization than of strategies and body organization than radially symmetrical sessile organismsradially symmetrical sessile organisms
Two major evolutionary advances in phylumTwo major evolutionary advances in phylum CephalizationCephalization
Concentrating sense organs in the head regionConcentrating sense organs in the head region Bilateral symmetryBilateral symmetry
Body can be divided along only 1 plane of Body can be divided along only 1 plane of symmetry to yield 2 mirror images of each othersymmetry to yield 2 mirror images of each other
First phylum with Right and Left sidesFirst phylum with Right and Left sides
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-3
General FeaturesGeneral Features
Acoelomates Acoelomates Typical acoelomates have only one internal Typical acoelomates have only one internal
space, the digestive cavityspace, the digestive cavity Without coelom (additional body cavity)Without coelom (additional body cavity)
TriploblasticTriploblastic Endoderm, Ectoderm, and MesodermEndoderm, Ectoderm, and Mesoderm 1st phyla to have 3 germ layers1st phyla to have 3 germ layers
ProtostomesProtostomes blastopore becomes the mouthblastopore becomes the mouth
Incomplete GutIncomplete Gut One opening One opening
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-4
Diagram of an Acoelomate Body Plan
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-5
Phylum PlatyhelminthesPhylum Platyhelminthes
CharacteristicsCharacteristics Commonly called Commonly called flatwormsflatworms Vary from a millimeter to many meters in Vary from a millimeter to many meters in
lengthlength Some free-living; others parasiticSome free-living; others parasitic
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-6
Stained Planaria
Terrestrial flatworm
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-7
Platyhelminthes is divided into Platyhelminthes is divided into three classes:three classes: Turbellaria (Planaria), Trematoda (flukes), and Turbellaria (Planaria), Trematoda (flukes), and Cestoda (tapeworm)Cestoda (tapeworm) All members of All members of Trematoda Trematoda (flukes)(flukes) and and CestodaCestoda
(tapeworms) are (tapeworms) are parasiticparasitic Class TurbellariaClass Turbellaria
Mostly free-living forms Mostly free-living forms Most are bottom dwellers in marine or Most are bottom dwellers in marine or
freshwaterfreshwater Freshwater planarians Freshwater planarians
Found in streams, pools, and hot springsFound in streams, pools, and hot springs Terrestrial flatworms limited to moist placesTerrestrial flatworms limited to moist places
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-9
Form and FunctionForm and Function Epidermis and Muscles Epidermis and Muscles
Most have Most have cellular, ciliated epidermiscellular, ciliated epidermis on a on a basement membranebasement membrane
Most turbellarians have Most turbellarians have dual-gland dual-gland adhesive organsadhesive organs Viscid gland cellsViscid gland cells fasten microvilli of anchor fasten microvilli of anchor
cells to substratecells to substrate Secretions of Secretions of gland cellsgland cells provide a quick provide a quick
chemical detachmentchemical detachment
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-10
Cross Section Of PlanariaTurbellaria
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-11
Releasing and Attaching (Viscid) Glands
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-12
Nutrition and DigestionNutrition and Digestion SomeSome have a mouth, pharynx, and intestine have a mouth, pharynx, and intestine In planariansIn planarians
Pharynx may extend through the ventral mouth Pharynx may extend through the ventral mouth Intestine has three branchesIntestine has three branches
One anterior and two posteriorOne anterior and two posterior Mouth of Mouth of trematodes (parasitic flukes)trematodes (parasitic flukes)
Opens near the anterior endOpens near the anterior end Pharynx is not extensiblePharynx is not extensible Intestine ends blindly, varies in degree of branchingIntestine ends blindly, varies in degree of branching
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-13
Structure of Planarian
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-14
Human Liver Fluke - trematode
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-15
Planaria (Turbellaria)Planaria (Turbellaria) Carnivorous and detect food by Carnivorous and detect food by chemoreceptorschemoreceptors Food trapped in mucous secretions from glandsFood trapped in mucous secretions from glands Wrap themselves around preyWrap themselves around prey Extend the pharynx to suck up bits of foodExtend the pharynx to suck up bits of food
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-16
Trematodes (parasitic flukes)Trematodes (parasitic flukes) Feed on host cells, cellular debris, and body Feed on host cells, cellular debris, and body
fluidsfluids Enzymes from the intestine are secreted for Enzymes from the intestine are secreted for
extracellular digestionextracellular digestion Phagocytic cells in gastrodermis complete Phagocytic cells in gastrodermis complete
digestion at digestion at intracellular levelintracellular level Undigested food egested out the pharynxUndigested food egested out the pharynx
Cestodes (tapeworm)Cestodes (tapeworm) Rely on the host’s digestive tract Rely on the host’s digestive tract Absorb digested nutrientsAbsorb digested nutrients
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-17
Excretion and OsmoregulationExcretion and Osmoregulation Flatworms have Flatworms have protonephridia protonephridia (kidney)(kidney)
Used for Used for osmoregulationosmoregulation Beating flagella drive fluids down collecting ducts Beating flagella drive fluids down collecting ducts
Wall of the duct beyond the Wall of the duct beyond the flame cellflame cell bears folds bears folds
or microvilli to resorb ions and moleculesor microvilli to resorb ions and molecules Majority of metabolic wastes Majority of metabolic wastes
Removed by Removed by diffusiondiffusion through body wall through body wall Collecting ducts join and empty at Collecting ducts join and empty at nephridioporesnephridiopores
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-18
Nervous SystemNervous System Subepidermal nerve plexusSubepidermal nerve plexus resembles resembles
nerve net of cnidariansnerve net of cnidarians One to five pairs of One to five pairs of longitudinal nerve longitudinal nerve
cordscords lie under the muscle layer lie under the muscle layer Freshwater planarians Freshwater planarians
Brain is a Brain is a bilobed cerebral ganglion (mass bilobed cerebral ganglion (mass of nerve cells)of nerve cells) anterior to the ventral nerve anterior to the ventral nerve cordscords
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-19
Sense OrgansSense Organs Ocelli Ocelli (light-sensitive eyespots)(light-sensitive eyespots)
Present in turbellarians, and larval Present in turbellarians, and larval trematodestrematodes
Tactile and chemoreceptive cells Tactile and chemoreceptive cells AbundantAbundant
StatocystsStatocysts (equilibrium) and (equilibrium) and rheoreceptors rheoreceptors (sense direction of water (sense direction of water currents)currents)
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-20
Reproduction and RegenerationReproduction and Regeneration
FissionFission Many turbellarians constrict behind the pharynx and Many turbellarians constrict behind the pharynx and
separate into two animalsseparate into two animals Each half regenerates the missing partsEach half regenerates the missing parts
Provides for Provides for rapid population growthrapid population growth RegenerationRegeneration
If the head and tail are cut offIf the head and tail are cut off Each end grows the missing part; it Each end grows the missing part; it retains polarityretains polarity
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-21
Nearly all are Nearly all are monoecious monoecious (hermaphroditic)(hermaphroditic) but cross-fertilize but cross-fertilize
Male StructuresMale Structures One or more testes are connected to one One or more testes are connected to one
vas deferensvas deferens The vas deferens runs to a seminal vesicleThe vas deferens runs to a seminal vesicle A nipple-like penis or extensible tentacle is A nipple-like penis or extensible tentacle is
the copulatory organthe copulatory organ
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-22
Turbellarians Turbellarians develop male and female develop male and female organs opening at a common pore organs opening at a common pore
After copulation, eggs and yolk cells After copulation, eggs and yolk cells enclosed in small cocoon enclosed in small cocoon Attach by a stalk to plantsAttach by a stalk to plants Embryos emerge and resemble little adultsEmbryos emerge and resemble little adults
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-23
Classification of Phylum PlatyhelminthesClassification of Phylum Platyhelminthes Class Turbellaria - planariaClass Turbellaria - planaria Class Trematoda - flukesClass Trematoda - flukes Class Cestoda - tapewormClass Cestoda - tapeworm
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-24
Class Turbellaria Class Turbellaria Mostly Mostly free-livingfree-living Range from 5 mm to 50 cm longRange from 5 mm to 50 cm long Very small planaria swim by Very small planaria swim by ciliacilia Others move by cilia Others move by cilia
Glide over a Glide over a slime trackslime track secreted by adhesive secreted by adhesive glandsglands
Rhythmical muscular waves pass backward Rhythmical muscular waves pass backward from the headfrom the head
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-25Different Intestinal Pattern of Turbellarians
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-26
Marine tubellarian
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-27
Classification of Phylum PlatyhelminthesClassification of Phylum Platyhelminthes Class Turbellaria - planariaClass Turbellaria - planaria Class Trematoda - flukesClass Trematoda - flukes Class Cestoda - tapewormClass Cestoda - tapeworm
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-28
Class TrematodaClass Trematoda All trematodes are parasitic flukesAll trematodes are parasitic flukes Most adults are Most adults are endoparasitendoparasiteses (inside) of vertebrates (inside) of vertebrates They resemble turbellaria but the They resemble turbellaria but the tegument (skin) tegument (skin)
lacks cilia in adultslacks cilia in adults Sense organs are Sense organs are poorly developedpoorly developed Adaptations for parasitism include:Adaptations for parasitism include:
Penetration glandsPenetration glands Hooks and suckers for adhesionHooks and suckers for adhesion Increased reproductive capacityIncreased reproductive capacity
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-29
General Trematoda Life Cycle General Trematoda Life Cycle Egg passes from definitive host and must Egg passes from definitive host and must
reach waterreach water Hatches into a free-swimming ciliated Hatches into a free-swimming ciliated
larva, the larva, the miracidiummiracidium Miracidium penetrates tissues of a snailMiracidium penetrates tissues of a snail
Transforms into a Transforms into a sporocystsporocyst Sporocyst reproduces asexually to form Sporocyst reproduces asexually to form
rediaredia Rediae reproduce asexually and form Rediae reproduce asexually and form
cercariacercaria
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-30
Cercariae emerge from the snail Cercariae emerge from the snail Penetrate a 2Penetrate a 2ndnd intermediate host (fish) intermediate host (fish) Develop into Develop into metacercariaemetacercariae (juvenile flukes) (juvenile flukes)
Metacercaria develop into Metacercaria develop into adultsadults when eaten by when eaten by definitive hostdefinitive host
Some serious parasites of humans and Some serious parasites of humans and domestic animals are trematodesdomestic animals are trematodes Example: sheep live fluke, human liver flukeExample: sheep live fluke, human liver fluke
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-31
Sheep Liver Fluke (Sheep Liver Fluke (Fasciola hepatica)Fasciola hepatica)
Adult fluke lives in bile passageways in the Adult fluke lives in bile passageways in the liver of sheepliver of sheep
Eggs are passed out in feces Eggs are passed out in feces MiracidiaMiracidia hatch and hatch and penetrate snailspenetrate snails to to
become sporocysts become sporocysts After After two generationstwo generations of of rediaerediae
Cercaria Cercaria encyst on vegetation and await being encyst on vegetation and await being eaten by sheepeaten by sheep
When eaten, When eaten, metacercariaemetacercariae develop into develop into young flukesyoung flukes
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-32
Clonorchis sinensisClonorchis sinensis: Human Liver Fluke : Human Liver Fluke Most important human liver flukeMost important human liver fluke Common in China, Japan, and Southeast AsiaCommon in China, Japan, and Southeast Asia Also infects Also infects cats, dogs, and pigscats, dogs, and pigs Adult fluke is 10–20 mm long with an oral and Adult fluke is 10–20 mm long with an oral and
ventral suckerventral sucker
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-33
ClonorchisClonorchis Life Cycle Life Cycle (Liver Fluke) (Liver Fluke) Adults live in Adults live in bile passagewaysbile passageways of humans and other of humans and other
fish-eating mammals (sexual reproduction occurs fish-eating mammals (sexual reproduction occurs here)here)
Eggs containing a Eggs containing a complete miracidiumcomplete miracidium are shed are shed into water with fecesinto water with feces
The eggs hatch only when ingested byThe eggs hatch only when ingested by snails snails of of specific generaspecific genera
Miracidium enters snail tissue and transforms into a Miracidium enters snail tissue and transforms into a sporocyst sporocyst
Sporocyst produces one generation of Sporocyst produces one generation of rediaerediae, which , which begin differentiation (asexual reproduction)begin differentiation (asexual reproduction)
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-34
Human Liver Fluke Life Cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-35
Rediae pass into the snail liverRediae pass into the snail liver Turns into Turns into tadpole-like cercariaetadpole-like cercariae
Cercariae escape into waterCercariae escape into water Make contact with fishMake contact with fish Bore into fish muscles or under Bore into fish muscles or under scalesscales Shed tail and Shed tail and turn into aturn into a metacercariae cyst metacercariae cyst
A mammal eats A mammal eats raw fishraw fish Cyst dissolves and flukes migrate up bile ductCyst dissolves and flukes migrate up bile duct
Heavy infection can Heavy infection can destroy the liverdestroy the liver and and result in deathresult in death
Control of parasitesControl of parasites Destroy snails and thoroughly cook fishDestroy snails and thoroughly cook fish
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-36
Schistosoma: Blood Flukes Schistosoma: Blood Flukes Over 200 million people infested with Over 200 million people infested with
schistosomiasis schistosomiasis Common in Africa, South America, West Indies, Common in Africa, South America, West Indies,
and the Middle and Far Eastand the Middle and Far East Sexes are Sexes are separateseparate 3 species with varied location: 3 species with varied location:
large intestinelarge intestine small intestinesmall intestine urinary bladderurinary bladder
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-37
SchistosomaSchistosoma Life Cycle Life Cycle Eggs discharged in human feces or urineEggs discharged in human feces or urine In water, eggs hatch as ciliated In water, eggs hatch as ciliated miracidiamiracidia Contact with a particular species of Contact with a particular species of snailsnail to to
survive survive In the snail, they transform to In the snail, they transform to sporocysts sporocysts Sporocysts produce Sporocysts produce cercaria cercaria directlydirectly Cercariae Cercariae escape the snailescape the snail and swim until and swim until
they contact they contact bare human skin bare human skin oror other host other host Cercariae Cercariae pierce the skinpierce the skin and shed their tails and shed their tails
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-38
Enter blood vessels and migrate to the Enter blood vessels and migrate to the hepatic portal blood vessels hepatic portal blood vessels (blood vessel (blood vessel from digestive tract to liver)from digestive tract to liver)
Develop in the liver and they migrate to Develop in the liver and they migrate to target sitestarget sites
Eggs released by females are extruded Eggs released by females are extruded through gut or bladder lining and exit with through gut or bladder lining and exit with feces or urinefeces or urine
Eggs that remain behind become Eggs that remain behind become centers of centers of inflammationinflammation
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-39
Blood FlukeLife Cycle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-40
Cut Liver of individual who dies from hematemesis
(vomiting blood). 180 adult flukes were found in autopsy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-41
Control: proper disposal of human wastes Control: proper disposal of human wastes Schistosoma dermatitis Schistosoma dermatitis (swimmer’s itch)(swimmer’s itch)
Occurs when cercariae penetrate an unsuitable Occurs when cercariae penetrate an unsuitable host such as a human (our immune system fights host such as a human (our immune system fights them off leading to inflammation -itch)them off leading to inflammation -itch)
Normal host many be a bird or other animalNormal host many be a bird or other animal
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-42
Lung Fluke - from uncooked crab meat
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-43
Classification of Phylum PlatyhelminthesClassification of Phylum Platyhelminthes Class Turbellaria - planariaClass Turbellaria - planaria Class Trematoda - flukesClass Trematoda - flukes Class Cestoda - tapewormClass Cestoda - tapeworm
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-44
Class Cestoda Class Cestoda Tapeworms have long flat bodies with Tapeworms have long flat bodies with scolexscolex
Holdfast structure with suckers and hooksHoldfast structure with suckers and hooks
Scolex is followed by a linear series of Scolex is followed by a linear series of reproductive units or reproductive units or proglottids proglottids
Lack a digestive systemLack a digestive system Lack sensory organs except for modified Lack sensory organs except for modified
ciliacilia
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-45
Tapeworm: Scolex is site ofattachment.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-46
Tegument of aTapeworm:
Many microthricheshelp increase surfacearea for absorption.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-47
Tegument is has no ciliaTegument is has no cilia Entire surface of cestodes is covered with Entire surface of cestodes is covered with
projections projections (microtriches)(microtriches) similar to similar to microvilli seen in the vertebrate small microvilli seen in the vertebrate small intestineintestine Microtriches increase the surface area for food Microtriches increase the surface area for food
absorptionabsorption
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-48
Nearly all cestodes require two hostsNearly all cestodes require two hosts Adult is parasitic in the Adult is parasitic in the digestive tract of the digestive tract of the
vertebratevertebrate Over 1000 species of tapeworms known, Over 1000 species of tapeworms known,
infecting almost all vertebratesinfecting almost all vertebrates Most tapeworms Most tapeworms do little harm to hostdo little harm to host
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-49
Taenia saginataTaenia saginata: Beef Tapeworm: Beef Tapeworm Lives as an adult in the digestive canals of humansLives as an adult in the digestive canals of humans Juvenile form found in intermuscular tissue of cattleJuvenile form found in intermuscular tissue of cattle Mature adults can reach over 10 meters in length Mature adults can reach over 10 meters in length
with over 2000 proglottids (segments conaining with over 2000 proglottids (segments conaining reproductive organs)reproductive organs)
Scolex has four suckers but no hooksScolex has four suckers but no hooks Gravid proglottidsGravid proglottids (with shelled, infective larvae) (with shelled, infective larvae)
pass in feces, singlepass in feces, single ProglottidsProglottids rupture as they dry rupture as they dry
Embryos are Embryos are viable for five monthsviable for five months and are picked and are picked up by grazingup by grazing
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-50
Beef Tapeworm Life Cycle - ContinuedBeef Tapeworm Life Cycle - Continued Cattle swallow shelled larvae that hatch as Cattle swallow shelled larvae that hatch as
oncospheresoncospheres Oncospheres use hooks to burrow through Oncospheres use hooks to burrow through
the intestinal wall into the intestinal wall into blood or lymph blood or lymph vesselsvessels
When they reach voluntary muscle, they When they reach voluntary muscle, they encyst to become “bladder worms” (cyst that encyst to become “bladder worms” (cyst that resembles a bladder) resembles a bladder)
When the infected meat is eaten, the cyst When the infected meat is eaten, the cyst wall dissolves and the scolex evaginates to wall dissolves and the scolex evaginates to attach to intestinal wallattach to intestinal wall
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-51
New proglottids develop in New proglottids develop in 2–3 weeks 2–3 weeks Infected individuals expel numerous Infected individuals expel numerous
proglottids dailyproglottids daily Infection can be avoided by eating only Infection can be avoided by eating only
thoroughly cooked beefthoroughly cooked beef
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-52
Life Cycle of Beef Tapeworm: From human feces, to grass, to cattle, to meat, to human.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-53
Dog Tapeworm: Shows 3 Proglottids (Reproductive segments)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-54
Other types of Tapeworm:Other types of Tapeworm: Taenia soliumTaenia solium: Pork Tapeworm: Pork Tapeworm Diphyllobothrium latumDiphyllobothrium latum: Fish Tapeworm: Fish Tapeworm Echinococcus granulosusEchinococcus granulosus: : Unilocular HydatidUnilocular Hydatid
Phylum PlatyhelminthesPhylum Platyhelminthes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
14-55
Dog Tapeworm: humans acquire disease by unsanitary habits associated with dogs. When eggs are ingested, larvae encyst in the liver, lungs, or other organs.
Cyst enlarges up to the size of a basketball.