Excretory system in Flatworms - SS2 Biology Lesson Note

Flatworms, also known as Platyhelminthes, have a relatively simple excretory system compared to more complex organisms. The excretory system in flatworms is primarily responsible for regulating osmotic balance and removing metabolic waste products. Here are the key components of the excretory system in flatworms:

1.       Flame Cells (Protonephridia):

·         Flame cells are specialized excretory cells found in flatworms.

·         They are named after their flame-like appearance due to the beating of numerous cilia on their surface.

·         Flame cells are scattered throughout the body of the flatworm and connected to tubules called protonephridia.

·         The beating cilia create currents that draw fluids containing waste products from the surrounding tissues into the protonephridia.

2.       Protonephridial Tubules:

·         The protonephridial tubules are a network of tubes connected to the flame cells.

·         The tubules collect the fluid and waste products from the flame cells and transport them to the excretory pore for elimination.

·         As the fluid passes through the tubules, essential substances like ions and water are reabsorbed, maintaining the osmotic balance of the flatworm.

3.       Excretory Pore:

·         The excretory pore is the opening through which the waste products, filtered by the flame cells and transported through the protonephridial tubules, are eliminated from the flatworm's body.

·         The excretory pore serves as the exit point for the excretory system.

·         In addition to the excretory system, flatworms also eliminate undigested food and other waste materials through a single opening called the pharynx or mouth. This opening serves both as an inlet for food and an outlet for waste elimination.

It is important to note that the excretory system of flatworms is relatively simple compared to more advanced excretory systems found in higher organisms. Flatworms lack more complex structures such as nephrons, as seen in the excretory system of vertebrates.