The phylum Platyhelminthes is a subclass of the kingdom Animalia. This phylum contains 13,000 different species. Flatworms are another name for the organisms in question. These organisms are known as acoelomates, and they include a wide variety of free-living and parasitic life forms.

A single-celled organism to approximately 2-3 feet in length is considered to be a member of this phylum.

Characteristics of Platyhelminthes

The following are some of the most important characteristics of Platyhelminthes:

1. They are triploblastic, acoelomated, and bilaterally symmetrical in their structure and function.
2. They may be free-living organisms or parasites on other organisms.
3. The body is covered with a soft covering that may or may not have cilia.
4. Their body is flattened dorsoventrally and lacks any segments, giving it the appearance of a leaf.
5. The anus and circulatory system have been removed from them, but they still have a mouth.
6. They breathe by simple diffusion across the surface of their bodies.
7. They are organised on an organ-level of hierarchy.
8. It is believed that they do not have a digestive tract.
9. The connective tissue parenchyma fills the space between the body wall and the organs, which aids in the transportation of food material.
10. They are hermaphrodites, which means that they have both male and female reproductive organs in the same body.

Unique Characteristics of Platyhelminthes

In order to differentiate organisms belonging to the phylum Platyhelminthes from others, the following characteristics must be present: 

• The presence of flame cells

• A nervous system that looks like a ladder.

• The presence of parenchyma in the intravascular space.

• Self-fertilisation

Classification of Platyhelminthes

The following is a list of the Platyhelminthes classifications: Turbellaria, Trematoda, Cestoda.

Turbellaria

• They are free-living organisms that can be found mostly in freshwater.

 • Their bodies are flattened dorsoventrally.

• There are no hooks or suckers to be found.

• Examples include Planaria and Otoplana.

Trematoda

• The majority of these are parasitic.

• Hooks and suckers are frequently encountered.

• For example, Fasciola hepatica and Diplozoon

Cestoda

Examples include Taenia spp. and Convoluta. 

• They are exclusively parasitic and have hooks and suckers on them.

A small number of organisms belonging to these species are capable of causing severe diseases such as Schistosomiasis or snail fever, among others. It is considered to be one of the most dangerous diseases in tropical areas. Another disease caused by tapeworms is taeniasis, which is a parasitic infection.

Examples of Platyhelminthes

The examples of organisms belonging to phylum Platyhelminthes are:

Dugesia (Planaria)

These can be found in freshwater ponds or slow-moving rivers and streams. Their bodies are covered in cilia, and they have the ability to regenerate the missing part. Its head is adorned with a pair of eyes as well as two lateral lobes.

Schistosoma

The term “blood fluke” refers to the fact that it is found in the mesenteric blood vessels and hepatic portal system of humans, and thus is named as such. It exhibits clearly defined sexual dimorphism.It is caused by the parasite Schistosoma, which is transmitted through contaminated water. Anaemia, pain, fever, liver and spleen enlargement, and diarrhoea are all symptoms experienced by the patient.

Fasciola

This parasite is also referred to as a liver fluke because it can be found in the liver and bile duct of sheep and goats. Despite the fact that it is a hermaphrodite, cross-fertilization occurs.Animals are affected by fascioliasis as a result of this substance. The liver of the animal enlarges as a result of this, and the bile ducts become blocked. The infection weakens the muscles of the animals, causing them to experience muscular discomfort. It is also possible that it will be fatal for the animals.

Taenia solium

It is also referred to as the pork tapeworm, and it can be found in all countries where pork is a staple food. They live as parasites in the small intestines of humans, and their larvae can be found in the muscles of pigs, which is where they get their name. It is a hermaphrodite, which means that it reproduces by fertilising itself.

Taenia solium is the cause of taeniasis, which manifests itself as abdominal pain, anaemia, indigestion, restlessness, and a false appetite in the patient.

Other organisms exist, such as Taenia saginata, which is transmitted through beef and lives in the intestines of cats and dogs, and Echinococcus granulosus, which lives in the intestines of humans and cats and dogs.

Conclusion

A flatworm, also known as a platyhelminth, is any member of the phylum Platyhelminthes are a group of soft-bodied invertebrates that are typically flattened in shape. A number of flatworm species are free-living, but approximately 80% of all flatworm species are parasitic, meaning that they live on or in another organism and obtain nourishment from it. These creatures are bilaterally symmetrical (that is, the right and left sides are identical) and lack specialised respiratory, skeletal, and circulatory systems; there is no body cavity (coelom) on either side of their bodies. The body is not segmented; spongy connective tissue (mesenchyme) makes up the so-called parenchyma, which fills in the spaces between organs and serves as a cushion between them.