Distinguish, differentiate, compare and explain what is the difference between Septal and Pharyngeal nephridia.
Difference between Septal and Pharyngeal nephridia
1. Septal nephridia occur in segment 15 onward. Pharyngeal nephridia occur in segments 4, 5 and 6.
2. Septal nephridia is attached to the septa. Pharyngeal lie on the sides of the gut.
3. Septal nephridia number varies from 80 to 100 per segment. There are only 3 pairs of pharyngeal nephridia.
4. Septal nephridia removea metabolic wastes from the blood and coelomic fluid. Pharyngeal nephridia removes metabolic wastes from the blood only.
5. Septal nephrdia discharge their excretory matter into lumen of alimentary canal. The duct of Pharyngeal nephridia of sixth segment open into buccal cavity while ducts of nephridia of fourth and fifth segment open into pharynx.