Biology » The Excretory System » Excretion Systems

Summarizing Excretion Systems


Many systems have evolved for excreting wastes that are simpler than the kidney and urinary systems of vertebrate animals. The simplest system is that of contractile vacuoles present in microorganisms. Flame cells and nephridia in worms perform excretory functions and maintain osmotic balance. Some insects have evolved Malpighian tubules to excrete wastes and maintain osmotic balance.


flame cell

(also, protonephridia) excretory cell found in flatworms

Malpighian tubule

excretory tubules found in arthropods


cellular processes that increase the surface area of cells


excretory structures found in annelids


pore found at the end of nephridia

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