Answer:
●Flatworm
Protonephridia: this are tubes that branch all through the body into bulb-like flame cells; only open to exterior and not the interior of the body; cilia take in fluid from the body; it helps in preventing loss of ions
Reabsorption of water and metabolic waste product
Excretion is aided by excretory pores
●Earthworms
(Meta)nephridia: its tube system open to both inward and outside area of the body; it iundergies the closed circulatory system
Filtration: derive fluid in coelom via nephrostomes (bigger molecules are not included)
Reabsorption of salt takes place in nephrostomes
Nephrostomes is also involved in secretions.
Excretion: urine is excreted through the nephridiopores
●Insects
Malpighian tubules: it is a continuation of digestive tract that branch off; urine is not produced by filtration due to the fact that no pressure difference (open circulatory system) occurs admist the blood in body cavity and tubules; and can preserve water till a large degree.
Reabsorption: water and K+ is recollected into circulatory system through the tubules.
Secretion will result in water absorption through osmosis
Secretion: substances such as waste molecules, Na+, and K+ have an inflow into the tubules through active transport
Excretion of small molecules and waste products take the appearance of feces