Question

Which of the following is the most complicated type of canal system which is absent in calcareous sponges?
A) Euryphylous leuconoid type
B) Aphodal leuconoid type
C) Diplodal leuconoid type
D) None of the above

Answer 1

The members of Porifera are referred to as sponges. Also, these sponges are diploblastic and leuconoid. They are considered to be most complex and also not all the chambers are necessarily flagellated.

Complete step by step answer: The calcareous sponges are said to be the smallest and simplest sponges and have correspondence. Within the diplodal system, a slender tube referred to as prosodus connects the incurrent channel additionally the flagellate chamber and there’s also an aphodus connecting the chamber to the excurrent channel. The diplodal system is leuconoid in nature and derived from a rhagon stage.
-In choice A is Eurypylous: In the eurypylous leuconoid style of the canal system, the flagellate chambers unit of measurement wide and thimble-shaped, each gap directly into the excurrent canal by a decent aperture remarked as apopyle and receives the installation direct from the incurrent canal through the prosopyle.
The current of water takes the next route
Dermal pores or Ostia areas subdermal areas → incurrent canals → prosopyles → flagellate chambers → apopyles —> excurrent canals spongocoel → osculum → out
This type of canal system is found generally in Leucilla.
-In option B is Aphodal: In the aphodal leuconoid sort of canal system, the flagellate chambers square measure tiny, and rounded. The gap of each flagellate chamber into the excurrent canal is drawn out into a narrow tube, sometimes not of nice length, termed aphodus. The relation between the flagellate chambers to the incurrent canals remains like before. The route of water current is as follows
Dermal pores or Ostia house subdermal house → incurrent canals → prosopyles → flagellated chambers → aphodus → excurrent canals→ spongocoel → osculum → out
This type of canal system is found in Geodia and Stella
-In option C is Diplodal: In some cases, besides a slim current tube, the prosodus between the incurrent canal and conjointly the appendage chambers, such a condition is called diplodal. This type of canal system is found in Oscarella, Spongilla, etc. The current of water takes the next route.
Dermal pores or Ostia areas subdermal areas → incurrent canals → prosodus → outgrowth chambers → aphodus → excurrent canals → spongocoel → osculum → out.
Hence, option C is the right answer.
Note: The main characteristics of the leuconoid variety of canal systems measure the limitation of the choanocytes to tiny chambers, the nice development of the mesoderm, and therefore the quality of the incurrent and excurrent canals.