Question

Members of Porifera phylum are commonly known as

• A. corals
• B. protozoa
• C. jellyfish
• D. sponges

Answer 1

Answer:

D. sponges

Phylum Porifera:

• Members of this phylum are commonly known as sponges. 
• They are generally marine (Except Spongilla, its fresh water sponge)
• Mostly asymmetrical animals
• These are primitive multicellular animals and have cellular level of organisation.
• Sponges have a 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.

Functions of water transport /canal system in sponges. This pathway of water transport is helpful in:

• Food gathering
• Respiratory exchange and
• Removal of waste

Water --> Ostia --> Spongocoel --> Osculum

• Choanocytes or collar cells line the spongocoel and the canals
• Digestion is intracellular
• The body is supported by a skeleton made up of spicules or spongin fibres.
• Sexes are not separate (hermaphrodite), i.e., eggs and sperms are produced by the same individual. 
• Sponges reproduce asexually by fragmentation and sexually by formation of gametes.
• Fertilisation is internal and development is indirect having a larval stage which is morphologically distinct from the adult.
• Examples: Sycon (Scypha), Spongilla (Fresh water sponge)