Phylum Platyhelminthes April Adams Zoology NCHS

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

Acoelomate Digestive cavity is the only inner cavity Ectoderm Mesoderm Endoderm Digestive cavity is the only inner cavity

Fig. 14.1

Acoelomate Phylum Platyhelminthes: Class Turbellaria Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Phylum Platyhelminthes: Class Turbellaria Acoelomate

Other Body Plans: Pseudocoelomate Ectoderm Mesoderm Endoderm Fluid 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 Ectoderm Mesoderm Endoderm Epithelial lined cavity between digestive tract and body wall

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 anterior ganglion sensory receptors transverse nerve cord Eye spot= detects light

Cephalization=“Primitive Brain” Auricle Cerebral ganglion Paired nerve cords

Excretory System Gets rid of nitrogenous wastes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Excretory System 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) Fig. 14.6a

Kingdom Animalia Phylum Platyhelminthes Classes:. Turbellaria Kingdom Animalia Phylum Platyhelminthes Classes: Turbellaria Trematoda Cestoda

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 Sexually: hermaphrodites Asexually: can regenerate missing body parts (called fission) each Planaria gives and receives sperm Detaches its tail end and each half regrows the lost parts What would happen ????

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 structures Digestive/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 ganglion Nerve cord Gastrovascular cavity Mouth pharynx Flame cells 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

Flukes Blood 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. Life Cycle of a Schistosome Fluke

Schistosome Cercaria have forked tail

Swimmers Itch

Clonorchis sinensis Oral sucker Intestine Uterus Yolk gland Ovary Seminal recepticle Testes

Clonorchis sinensis Chinese liver fluke 50 million people Cirrhosis of liver Diarrhea Edema Pain

Fig. 14.12

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. Life Cycle of the Sheep Liver Fluke

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 Testes Uterus Vas deferens Seminal receptacle Ovary Yolk gland

Pork Tapeworm (Taenia solium) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pork Tapeworm (Taenia solium)

Taenia saginata

Life Cycle of the Broad Fish Tapeworm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Life Cycle of the Broad Fish Tapeworm Diphyllobothrium latum Source: Redrawn From Centers for Disease Control, Atlanta, GA.

Dipylidium caninum

Echinococcus granulosus Parasite of dogs Host Juveniles in sheep, man and other mammals Intermediate host Hydatid cyst

Hydatid Cyst Cysticercus Juvenile stage

Ecinococcus granulosus Adult stage in dog