Question

Solenocytes are the main excretory structures in
A. Annelids
B. Molluscs
C. Echinoderms
D. Platyhelminthes.

Answer 1

Hint:Solenocytes are extended, flagellated cells which serve in elimination of nitrogenous wastes and found in most of lower invertebrates such as platyhelminthes. Solenocytes are also known as Flame cells.


Complete answer:
To answer this question, first, we need to know about solenocytes. Solenocytes are flagellated cells involved with excretion, ion regulation and osmoregulation lots of animals and in some chordates which come belong to the subphylum Cephalochordata. These are the cells that form subtypes of protonephridium along with the other type i.e. flame cells. It is a cup formed cell that includes group of cilia and this is the main excretory organ of platyhelminthes.
Now, let us find the solution from the option.
Solenocytes are meant for excretion and osmoregulation in Platyhelminthes.
Most annelids and molluscs have nephridia which are tubules unblock at both sides. The interior unblocking opens into coelom whilst exterior unblocks externally as nephridiopores.
In echinodermata, there are no specific excretory organs present for excretion. In them, excretion carries out via the process of diffusion or osmosis or via active transport mechanism.

Thus, the correct option is D i.e. Platyhelminthes.

Note:Solenocyte is obtained from mesoderm; it is an extended or lengthy cell with a constantly moving long flagellum which wafts excretory products through the tubule. The walls of the tube are thin and consist of pillar-like rods. The excretory liquid is formed by ultra-purification of body fluids via the wall.