Question

Many sponges may be bigger than fishes, yet they do not have respiratory organs because they

• A. Are sedentary
• B. Have porous body
• C. Respire anaerobically
• D. Do not require them

Answer 1

The correct option is B Have porous body

Sponges lack respiratory system. Hence, they have a different mechanism for gaseous exchange. The body of sponges is porous and is covered by numerous pores. There are numerous ostia, through which water enters the body from outside and a single osculum, through which water flows out of the body. In this way, oxygen is used up as the water enters the body of sponges.

So, the correct answer is 'Have porous body'.'.