Platyhelminthes or flatworms are dorsoventrally flattened bilaterally symmetrical tripoblastic but acoelomate animals which have a blind sac body plan.There are about 13,000 species, most of which are parasitic, a few commensal or free living. The free living forms occur in both fresh water and marine habitats.
Phylum Platyhelminthes is divided into three classes
- Class: Trematoda
- Class: Turbellaria
- Class: Cestoda
This class includes a group of parasites that infect various animals including man. Body is specialised for parasitic mode of life.
Example-Fasciola hepatica (Liver fluke), Schistoma (Blood fluke)
Fasciola hepatica (Liver fluke)
It is an endoparasite found commonly in the bile ducts of sheep, goats and cattle causing the disease liver rot. Liver fluke is a hermaphrodite and the life cycle is completed in two hosts, viz., a primary vertebrate host an intermediate host called the water snail Limnaea truncatula. Most of them are brilliantly coloured.
Schistoma are human parasites popularly known as blood flukes. The infections caused by them are generally known as Schistosomiasis. Intermediate host of schistosoma is snail. Three species of Scistoma(S.haematobium, mansoni, japonicum)are found to be pathogenic in man.
This class includes mostly free living flat worms. Most of them are aquatic and bottom dwellers, few are pelagic and some are terrestrial.
It is a free living flat worm found in ponds and streams. It is about 2 cm in length. The animal is brightly colored and the color varies in the same species in different environments. The planarians show remarkable ability of regeneration. A small piece of the body grows to a full animal.
This class includes tape worms which are the intestinal parasites of vertebrates.
Example-Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm)
Taenia solium (Pork tapeworm)
It is a human parasite. The intermediate host is pig. Incidences of tapeworm infection are common all over the world in places where pork is eaten without proper and adequate cooking.
Taenia saginata (Beef tapeworm)
It is also a human intestinal parasite but the intermediate host is the cattle. Infection occur mainly by taking improperly cooked beef.
- MCQ on Zoology
MCQs on Animal Kingdom(Phylum Porifera-Phylum Chordata)
- Example of Non Chordata
Non Chordata : Characteristics with Examples
- Example of Chordata
Phylum Chordata with examples
- Phylum Platyhelminthes : General Characters
General Characters of Phylum Platyhelminthes
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- Phylum Cnidaria (Coelenterata): General Characters and more
Phylum Cnidaria (formely known as coelenterata) includes about 9000 species.Some are found in fresh water, but the grater number are marine. Coelenterates (Gr. koilos, hollow+enteron,gut).are the simplest of eumetazoans. This interesting group of ani
- Phylum Porifera: General Characters and more
The Phylum Porifera include more than 5000 animal species, mostly marine, but includes about 150 fresh water inhabitants also. They found in all seas, wherever there are rocks, shells, submerged timbers, or coral to provide a suitable substratum. Mos
- Keystone Species
Keystone species refers to an organism that plays a critical role in its environment, one that may become apparent only once it is removed from an ecosystem.
Richman Thomas on April 26, 2017:
Wow! Great work for a visual learner.
dishita on April 05, 2016:
Deena (author) from India on January 23, 2013:
Thank you very much for your visit and comment.
Without image the topic is incomplete , that's why I put it there.
Dianna Mendez on January 18, 2013:
Well, I find this interesting but it also makes me squirm seeing these worms. Great write up and learned something today.