Question

Excretory organs of Amphioxus are
A. Nephrons
B. Flame Cells
C. Nephridia
D. Kidneys

Answer 1

A passive biological mechanism that eliminates excess, unwanted materials from the body fluids of an organism is the excretory system. Amphioxi are small marine species widely found in the warmer parts of the world's coastal waters and less often in temperate waters. Typical chordate characters, such as a dorsal hollow neural tube and notochord, have Amphioxus.

Complete answer:
A nephron is the microscopic functional and operational unit of the kidney. Flame cells are specialized excretory cells found in the simplest freshwater.
Kidney is a bean shaped organ having the ability to remove fluid wastes.
Nephridium is an excretory organ that acts in vertebrates in a similar way to a kidney. These are present in invertebrates in a paired form. It is also found in Amphioxus. This expels waste from the cavity of the body to the outside.
In the form of mesodermal kidneys, Amphioxus or Branchiostoma is an unusual chordate species which does not have excretory organs, but is in the form of protonephridia.
They are similar to flat worm or polychaete, annelid protonephridia and are of ectodermal origin.
In Amphioxus, one above each gill slit on either side, there are 90 to 100 pairs of protonephridia present segmentally on the dorso-lateral pharyngeal wall. Simply, as structures, they are ciliated, thin walled, closed ectodermal tubules.

Hence, the correct answer is option (C).

Note: Many organs and organ systems include lancelets that are closely similar to those of modern fish, but in more primitive types. They give a variety of examples of potential evolutionary exaptation, therefore. The gill-slits of lancelets, for example, are used only for feeding and not for respiration. The circulatory system brings food across the body, but the oxygen delivery system does not include red blood cells or hemoglobin.