Question

In Demospongiae skeleton is composed of

• A. Spongin fibers
  
• B. Silicious spicules
• C. Both A and B
• D. Keratin fibres
  

Answer 1

Answer: (C)

Both A and B

The Demospongiae are the largest class in the phylum Porifera. They are predominantly leuconoid in structure. Their "skeletons" are made of spicules consisting of fibers of the protein spongin, the mineral silica or both. Where spicules of silica are present, they have a different shape from those in the otherwise similar glass sponges.

So, the correct answer is option C.