Question

What is the skeleton of sponges made up of?

Answer 1

Hint: Sponges are the members of the phylum porifera which means pore bearing organisms. They are multicellular organisms in which the circulation of water takes place through pores. The internal skeleton which are Skelton like fragments.

Complete answer:
The sponges appear and grow like plants. The sponges are multicellular heterotrophs which do not have cell walls. They do not have true tissue and organ system. They are asymmetrical with few of them radially symmetrical. They do not have nervous, circulatory or digestive system. They mostly feed on small bacteria. The constant flow of water through their body helps in obtaining food, oxygen and other nutrients and this entry and exit of water is through the osculum.

The sponges have the internal skeleton made up of spicules or spongin. They are basically the calcium carbonate or silicon fragments. This makes their body flexible. The presence of spicules gives a rough appearance to the sponge as they cone out of the body wall.

Based on the spicules the sponges are divided into-
A) Calcarea- They have skeleton which results in the cylindrical shape of the body.
B) Hexactinellida- They have six types of rayed glossy spicules.
C) Desmospongiae- They have colorful pigments and the skeleton may or may not be present.

The different types of spicules are shown below:

The correct answer is the skeleton of sponges is made up of spicules.

Note: These organisms are aquatic and are found in shallow deep water. Reproduction takes place both by sexual(fusion of sperm and egg)and asexual modes like budding and fragmentation. They have the power of regeneration.