or Flatworms

Characteristic of Platyhelminthes

Phylum Platyhelminthes contains about 20,000 species of soft-bodied, bilaterally symmetrical, invertebrate

They are commonly called flatworms.

Platyhelminthes are mostly worm like creatures

Bilaterally symmetrical.
Body having 3 layers of tissues with organs and organelles.

Body contains no internal cavity.

It Possesses a blind gut (it has a mouth but no anus)

Mostly they feed on animals and other smaller life forms.

Platyhelminthes are an ancient phylum, but practically nothing is known of their evolutionary history because they have very soft bodies which do not preserve well as fossils.

Interesting Facts

  • Tapeworms can be in sizes longer than a school bus. The longest one found was 90 ft.
  • They are estimated to live in 200 million humans around the world
  • One Fluke can produce over 500,000 embryos.
  • The stomach is like a sack. The food goes into the sack through the mouth. Once the food is taken into the body, the rest is thrown back out of the mouth. (They have no anus).

  • About 80% of flatworms are parasitic

New Zealand Platworm

It can vary from 5 mm in length when hatched to approximately 17 centimetres in mature adults.


TapeWorms are sessile which mean they cannot move on their own.
At least 125 million humans are infected with the tapeworm disease.

TapeWorms can infect all kinds of mammals.

When a single individual is divided into two or more parts, each part can regenerate an entire new tapeworm.

To kill TapeWorms, you have to use a treatment called quinacine hydrochloride or niclosadime.


Each fluke can cause the loss of 0.5 ml of blood per day from the liver.

Fluke infestation depresses appetite and consequently decreases weight gain.

The Blood Fluke
Tapeworms! Finally, a Parasite that's Gross, AND Harmful!