What is "nephridium"

Nephridium \Ne*phrid"i*um\, n.; pl. Nephridia. [NL., fr. Gr. ? of the kidneys.] (Zo["o]l. & Anat.) A segmental tubule; one of the tubules of the primitive urinogenital organs; a segmental organ. See Illust. under Loeven's larva.

(plural nephridia), 1877, Modern Latin, from Greek diminutive of nephros "kidney" (see nephron).

n. 1 (context biology English) a tubular excretory organ in some invertebrates 2 (context anatomy English) the embryonic excretory organ that develops into the kidney

The nephridium (plural nephridia) is an invertebrate organ which occurs in pairs and performs a function similar to the vertebrate kidney. Nephridia remove metabolic wastes from an animal's body. They are present in many different invertebrate lines. There are two basic types, metanephridia and protonephridia, but there are other types.