A nephridiopore is part of the nephridium, an excretory organ found in many

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s, such as

flatworm Platyhelminthes (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a Phylum (biology), phylum of relatively simple bilaterian, Segmentation (biology), ...

s and

annelid The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to vario ...

Polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...

typically release their gametes into the water column using nephridiopores. Nephridia are homologous to

nephron The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structu ...

s or uriniferous tubules found in the kidney of humans. Nephridiopores are present in ventral region. The nephridium consists of an opening called the nephrostome, a long convoluted tubule, and another opening called the nephridiopore. Body fluids are filtered in through the nephrostome and passed through the convoluted tubule system. Essential substances are reabsorbed through active mechanisms and waste products are secreted back into the lumen of the tube. The resulting excretory fluid or

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

is passed out through the nephridiopore.

References

Platyhelminth anatomy Annelid anatomy {{animal-anatomy-stub