Question

Organisms found in marine habitats, with skeletal spicules made of calcium carbonate, spongin or silica, multicellular diploblastic body riddled with ostia, chambers and canals, belong to

• A. Coelenterata
• B. Porifera
• C. Ctenophora
• D. Annelida

Answer 1

Answer: (B)

Porifera

Porifera is multicellular organisms, which are sedentary in nature. Most of them are marine.
The body wall is diploblastic, which consists of an outer layer, called as pinacoderm and an inner layer, called as choanoderm.
The canal system mainly comprises of incurrent and excurrent canals, which are lined with pinacocytes and radial canals, which are lined with choanocytes (flagellated cells).
The body walls contain numerous pores, called as Ostia through which water enters the body through a canal system into the central body cavity called as the spongocoel.
Sponges have an exoskeleton, which is made up of either spongin fibers or calcareous/siliceous spicules or a combination of both.

So, the correct answer is option B.