Question

Excretory organs of protochordate Amphioxus are

• A. Malpighian tubules
• B. Protonephridia
• C. Kidney
• D. None of the above

Answer 1

The correct option is B Protonephridia

Amphioxus or Branchiostoma is a peculiar chordate animal, which does not have excretory organs in the form of mesodermal kidneys but are in the form of protonephridia. They are similar to protonephridia of flat worms or polychaete, annelids and they are ectodermal in origin. In Amphioxus there are 90 to 100 pairs of protonephridia present segmentally on dorso-lateral pharyngeal wall one above each gill slit on either side. Simply, they are ciliated, thin walled, closed ectodermal tubules like structures.