View
221
Download
1
Category
Preview:
Citation preview
Phylum Platyhelminthes
Zoology WCHS
Phylum Platyhelminthes• Flat worms• Triploblastic= 3 tissue
layers• Acoelomate• Bilateral symmetry• Hermaphroditic• 1 opening for digestion• Simple nervous and
muscular systems• Flame cells• May be free living or
parasitic• CEPHALIZATION
AcoelomateAcoelomate
EctodermMesodermEndoderm
Digestive cavity is the only inner cavity
Phylum Platyhelminthes: Class Turbellaria
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Acoelomate
Other Body Plans:PseudocoelomateOther Body Plans:Pseudocoelomate
EctodermMesodermEndodermFluid filled cavity between the endoderm and ectoderm- pseudocoelom
Differs from a true coelom because…. • It is not entirely lined with mesoderm tissue• Organs are not suspended or attached to membranes
(mesenteries)
Other Body Plans:Coelomate
Other Body Plans:Coelomate
EctodermMesodermEndoderm
Epithelial lined cavity between digestive tract and body wall
8
Flatworm Body Systems
• No Circulatory or Respiratory systems- simple diffusion through body wall
Systems Present-• Digestive• Nervous • Excretory • Reproductive
Flatworm Body Systems:Digestive
Incomplete-• mouth • pharynx (to swallow
food) • intestine(no anus)
Nervous System
Lateral nerve cord
Eye spot= detects light
anterior ganglion
transverse nerve cord
sensory receptors
Cephalization=“Primitive Brain”Cephalization=“Primitive Brain”
Auricle
Cerebral ganglion
Pairednerve cords
Excretory System
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- Gets rid of nitrogenous wastes
- protonephridia- first kidney
Components:- Flame cells- Excretory
ducts/tubes- pores
Reproductive System • Sexual and asexual
reproduction sexual- eggs + sperm asexual- regeneration
• Hermaphrodites- both male (penis and testis)
and female organs(vagina and ovary)
Kingdom AnimaliaPhylum PlatyhelminthesClasses:
TurbellariaTrematodaCestoda
Class Turbellaria
• Most free-living• Aquatic• Eye spots• Regenerate if cut
in two• Ex. Planaria
Planarians
• Free-living flatworm • bilateral symmetry• Lives in fresh water
usually under leaves and rocks
• Usually feeds on dead or slow moving organisms
Planarian Reproduction
Reproduction:• Sexually:
hermaphrodites
• Asexually: can regenerate missing body parts (called fission)
What would happen ????
Detaches its tail end and each half regrows the lost parts
each Planaria gives and receives sperm
Planarians: body structures• Nervous/sensory system: Brain-like structure• Nerve cord: carries impulses down body• Eyespots: sense light and dark• Sensory pits: line sides of head to aid in
movement and sensing surroundings• Flame Cells: remove excess water and
nitrogenous wastes
Planarians: body structuresDigestive/excretory system
• Mouth: located in center of ventral side
• Pharynx: tube like structure which extends from mouth during feeding; acts like a straw sucking up food and carrying it to body
• Food enters mouth and solid wastes exit mouth
eyespot
ganglion
Gastrovascular cavity
Mouth pharynx
Flame cells
ganglion
Nerve cord
LABEL YOUR PLANARIAN!!!
Class Trematoda• Parasites• Holdfast devices
– Endoparasites• Complex life cycle- larval
stage in one or more hosts
Primary host-juvenile/larva stage-
sexual reproduction
Secondary host- adult stage, asexual reproduction
Ex. Blood and liver flukes
FlukesBlood fluke life cycle:• Eggs are released in water
from wastes of infected host• Hatch in to swimming larvae
in water• Larvae enter a host (like a
snail) where they develop & mature
• Enter water again and bore into skin of new host (man)
• From the blood stream they bore into intestines where they attach and feed on blood
Schistosoma
• Blood flukes• 200 million people• 1 million deaths/year
Life Cycle of a Schistosome Fluke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Schistosome
• Cercaria have forked tail
Swimmers Itch
Clonorchis sinensishuman liver fluke
Oral sucker
Intestine
Uterus
Yolk gland
Testes
Ovary
Seminal recepticle
Clonorchis sinensis
• Chinese liver fluke• 50 million people• Cirrhosis of liver• Diarrhea• Edema• Pain
Fascioloa hepatica
• Sheep liver fluke• Sheep, cattle and
man– Weight loss
• Eat contaminated vegetation
Life Cycle of the Sheep Liver Fluke
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Paragonimus westermani
• Lung fluke• Carnivores, pigs,
rodents and man• May be fatal
Class Cestoda: “cess pool”
• Tape worms• All parasitic• Live in intestines of
vertebrates• No digestive system• 40 feet long
Tapeworm structures• Scolex= head• hooks and suckers to
aid in attachment to intestine
• Proglottids: individual parts of worm– Each one is detachable– Each proglottid may
contain up to 100,000 eggs which fall off when full
– When released, they exit with the host’s wastes
Tapeworm life cycle• Eggs hatch in intestines of
intermediate host (pig or cow)• Young worms burrow out of
intestine into pig’s muscle tissue forming cysts
• Secondary host (man) eats undercooked/raw meat containing worm larvae cysts
• Larvae hatch and mature in intestines
• Attach to intestines, soak up digested food of host
• May enter bloodstream and infect other tissues
Scolex
Proglottid
Uterus
Testes
Ovary
Yolk gland
Vas deferens
Seminal receptacle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pork Tapeworm (Taenia solium)
Taenia saginata
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Source: Redrawn From Centers for Disease Control, Atlanta, GA.
Life Cycle of the Broad Fish Tapeworm
Diphyllobothrium latum
Dipylidium caninum
Echinococcus granulosus
• Parasite of dogs– Host
• Juveniles in sheep, man and other mammals– Intermediate host
• Hydatid cyst
Hydatid Cyst
• Cysticercus – Juvenile stage
• Adult stage in dog
Ecinococcus granulosus
Recommended