Flatworms Phylum Platyhelminth

Endoparasite

Exoparasite / Ectoparasite

Life cycles Most parasitic worms have more than one organism in their life cycle: An intermediate host (the first), usually a mollusk Sometimes there are multiple intermediate hosts A final (definitive host), usually a vertebrate These hosts are where sexual reproduction occurs

Clonorchis

Flatworms Name means flat worm

Flatworm advancements First animals to show bilateral symmetry First animals to have 3 well defined germ layers (called tripoblastic) Are considered acoelomate (no body cavity) Simple sense organs with eye spots in some

Advancements, continued First animals to show cephalization – having a clear and defined head with most of the important structures found there First to have an excretory system First to have a circulatory system with blood

Characteristics Oral and genital structures found mostly on the ventral surface Digestive system incomplete Simple sense organs Nervous system with a central processor (brain) Most organisms monoecious, some with complicated life cycles

Class Turbellaria Planarians Free living Most often found in fresh water Eyespots sense light

Some can split asexually by fission

Planarian

Planarian Pharynx is responsible for obtaining food Extends out and releases proteolytic enzymes (breaks down protein) External digestion

Class Trematoda Parasitic flukes Generally endoparasites Poorly developed sense organs Generally have suckers but no hooks

Life cycle of the liver fluke

Fluke

Paragonimus westermani The lung fluke parasite Causes paragonimiasis

Clonorchis

Clonorchis Common in the Orient Can cause cirrhosis of the liver

Schistosomiasis

Schistosomiasis Blood fluke 200 million people infected Causes severe dysentery, anemia, bladder inflammation and brain damage There is also a kind that infects birds that causes “swimmer itch” a rash

Class Cestoda Tapeworms Long flat bodies made up of an attachment head with hooks and suckers, called scolex The scolex is followed by MANY reproductive segments called proglottids

Tapeworms Completely lack a digestive system and sense organs Generally have more than one host

Tapeworm cyst in the liver

Beef Tapeworm Larvae shed from the human host are eaten by cattle Larvae hatches and encysts in the muscle People eat un- or undercooked meat and the larvae hatches in the intestines

Dog Tapeworm

Pork Tapeworm - Taenia solium

Question…… What is the world's longest parasite? The world's longest parasite is the tapeworm so the next question is 'What is the world's longest tapeworm?' The longest tapeworm ever removed from a human came out of Sally Mae Wallace on September 05, 1991. In all, doctors pulled 37 feet of tapeworm out of Sally Mae Wallace's body If you find all of this disgusting, be glad you're not a whale as tapeworms in whales can grow up to 120 feet long.

You need: Planaria – digestive or plain Clonorcis Schistosome Taenia