Question

Difference between sponges and other metazoan is
A) Sponges do not contain blood
B) Sponges possess cellular level of organization
C) Sponges do not have cell division
D) Sponges do not have division of labour

Answer 1

Much of them are marine, with the exception of the Spongillidae family of 150 freshwater sponges. In general, these sedentary species live in low depths and use firm surfaces for attachment, but glass sponge approaches greater depths and anchors on sediments.

Complete answer:
First we should know about the sponges to answer this question. Sponges belong to Phylum Porifera. Sponges are asymmetrical or radially symmetrical superficial metazoa with such a cellular hierarchical grade lacking tissues, organs, a porous body and a channel structure lined with choanocytes.
Now, let us find the solution from the options-
- In some and most cases, via the folding of the spongocoel base, the interior of sponges has a clear hollow cavity named the spongocoel or paragastric cavity filling the microvillous collard choanocytes, countless water canals form a complex network (canal system) that pushes water via the canals and transmits food and oxygen. Thus, option A is not the correct option.
- Sponges have cellular organisational levels and are thus considered among the metazoans to be the simplest types. They consist of only a few cells that are specialised yet poorly coordinated, displaying no coordination. This constraint to the cellular stages of the organisation of the body suggests that the tasks are done by individual cells or cell aggregates.
- They all have some structural properties in common. The body is made up of loose accumulation of different cell types that barely shape any tissue. No organ or organ system remains. The mouth and the digestive cavity are absent. Vital tasks are conducted by the cells' autonomous activities. Thus, option C is not the correct option.
- The mesenchyme is the existence of a middle gelatinous, non-living layer comprising amoeboid cells and supporting skeletal components. Mesophyll refers to some metazoans' connective tissue. Thus, option D is not the correct option.

Thus, the correct answer is option (B) Sponges possess cellular level of organization.

Note: For the same reason, specialized bodies, named gemmules, are produced in freshwater sponges. For a period spanning from two months to 3 years, the gemmules remain effective.