In: Biology
Describe how filtration occurs in metanephridia within the body of earthworms?
In a metanephridium, there is a ciliated funnel covered with a membrane that helps to filter the hemocoel of heavy particles (such as proteins and carbohydrates) before the fluid even enters the funnel.
In either form, the cilia or the flagellum wave filtered urine down the tube to the outside. The metanephridium tubule lacks a flame cell and opens directly into the body cavity. Cilia lining the tubule draw up cavity fluids and conduct them to the exterior.
These ciliated tubules pump water carrying surplus ions, metabolic waste, toxins from food and useless hormones out of the organism by directing them down funnel shaped bodies called nephrostomes. Body fluid is drawn in from the nephrostome, substances are filtered, selected or reabsorbed as necessary
In earthworms, nephridia filter fluid from the coelom, or body cavity. Beating cilia at the opening of the nephridium draw water from the coelom into a tubule. As the filtrate passes down the tubules, nutrients and other solutes are reabsorbed by capillaries.