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

PlanariansFree livingMost often found in fresh waterEyespots 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