Describe the body structure of sponges.

Sponges are asymmetrical with cellular level of organization.

They have water transport system. Water enters into the spongocoel (cavity) through minute pores called ostia. Water comes out through a common opening called Osculum. This system helps in taking in food, respiration and also excretion. Specialised cells called Coenocytes line the cavity. Skeleton is made up of spicules or spongin fibres.