2003 AIPMT Animal KingdomPhylum Porifera Easy Question 3 of 3 in Phylum Porifera

Sycon belongs to a group of animals, which are best described as : -

A Unicellular or acellular
B Multicellular without any tissue organization
C Multicellular with a gastrovascular system
D Multicellular having tissue organization, but no body cavity

The answer is B.

Solution

Sycon (Scypha) is a sponge, belonging to phylum Porifera.
Sponges are multicellular animals, but their cells are loosely aggregated and do not form true tissues. This is the cellular level of organisation.
Instead of a gut, they have a water canal system (ostia, spongocoel, osculum) lined by collar cells (choanocytes); there is no gastrovascular cavity (that is found in cnidarians).
So Sycon is best described as multicellular without any tissue organisation.

Concept Cellular level of organisation in sponges

Phylum Porifera in past papers

3 questions from this chapter have appeared across 3 exam years.