Question

Presence of spicules, pores in the body and a single cavity are the characteristics of the phylum___________.

• A. Porifera
• B. Mollucsa
• C. Echinodermata
• D. Chordata

Answer 1

The correct option is A Porifera

Sponges belong to phylum Porifera because they have a perforated body and water transport or canal system. Water enters through minute pores (ostia) in the body wall into a central cavity, spongocoel, from where it goes out through the osculum. This pathway of water transport is helpful in food gathering, respiratory exchange, and removal of waste. Perforations are due to Ostia in the body of sponges.

The internal skeleton of the sponges is made up of spicules. The classification of phylum Porifera is based upon spicules.

They are divided into 3 classes:

1. Class Calcarea, in which a skeleton is made up of calcareous spicules. e.g., Leucosolenia, Sycon, etc.

2. Class Hexactinellida, in which skeleton contains six-rayed, or triaxon, siliceous spicules. e.g., Euplectella, Hyalonema.

3. Class: Demospongiae, in which skeleton either absent or present. The skeleton contains spongin fibers or siliceous spicules or both. e.g., Oscarella, Cliona, Euspongia, etc.