Key Characteristics
*Flatworms are dorsoventrally flattened acoelomates with bilateral symmetry
*They are the simplest animals to be triblastic
*They have moderate cephalization sometimes called a head
*Have tissues, organs, and organ systems
*Their flat shape places all cells close to their surroundings allowing gas exchange and elimination of wastes
*Flame cells are used to regulate osmotic balance
*Have a pharynx
*There are 20,000 species
Habitat
The platyhelminthes are mostly ecto or endoparasitic and few are free-living. The free-living ones belong to the class Turbellaria and live in freshwater, ponds, lakes, streams and springs. Some of them are found in shores in tropical and subtropical regions. Trematoda and cestoda are parasites. In adult stage they parasitise vertebrates and in larval stages they occur as parasites of the invertebrate animals.
Interesting facts
1. Platyhelminthes are sometimes used to control invasive species.
2. The most popular form of flat worms are tapeworms.
3. Tapeworms live in the digestive track of their host
4. Non-parasitic flatworms live in wet environments like damp terrestrial habitats
5. polycladida are non-parasitic flat worms that live in coral reefs
Five examples
1. Polycladida
*Flatworms are dorsoventrally flattened acoelomates with bilateral symmetry
*They are the simplest animals to be triblastic
*They have moderate cephalization sometimes called a head
*Have tissues, organs, and organ systems
*Their flat shape places all cells close to their surroundings allowing gas exchange and elimination of wastes
*Flame cells are used to regulate osmotic balance
*Have a pharynx
*There are 20,000 species
Habitat
The platyhelminthes are mostly ecto or endoparasitic and few are free-living. The free-living ones belong to the class Turbellaria and live in freshwater, ponds, lakes, streams and springs. Some of them are found in shores in tropical and subtropical regions. Trematoda and cestoda are parasites. In adult stage they parasitise vertebrates and in larval stages they occur as parasites of the invertebrate animals.
Interesting facts
1. Platyhelminthes are sometimes used to control invasive species.
2. The most popular form of flat worms are tapeworms.
3. Tapeworms live in the digestive track of their host
4. Non-parasitic flatworms live in wet environments like damp terrestrial habitats
5. polycladida are non-parasitic flat worms that live in coral reefs
Five examples
1. Polycladida
2. Tapeworms
3. Flukes
4. Planaria
5. Monogenea
In this video, he explains what exactly a platyhelminthes is, and shows a few examples of them. One strength of this video is that it has many visuals and not all text or talk. One weakness is that the video's content is minimal and doesn't tell us much more than what it is.