The Phylum Porifera shelters aquatic individuals, without locomotor structures, and that live attached to the substrate: the porifera, or sponges, also called sponges. Their color, size and shape vary greatly. Simpler sponges are classified as the ascon type; and appear similar to hollow cylinders, with an opening at the upper end: the osculum. Asconoids are lined externally by two types of cells: pinacocytes and porocytes. These have pores, being responsible for the entry of water directly into the sponge; those, on the other hand, are flat cell types that are well joined together.
The internal region, called spongiocele, is made up of choanocytes, which are cell types with flagellum, responsible for moving water inside the animal, and also for its digestion. Between these two layers there is the meso-hilum, composed of gelatinous substance and cells responsible for digestion, fabrication of support structures, and also for the formation of all cell types of these animals.
There are also more complex sponges: the syconoids, or the sycon type. In these, the wall is thicker, and there are slits through which the water passes into the internal medium and is then directed to the afferent channels. That’s where the porocytes are. These direct the water to the radial canals, which are lined by the choanocytes, and the force of the flagella of these cells causes the water to go to the spongiocoel and then be eliminated by the osculum.
Leuconoid sponges are the third and final type. They are larger and the body structure is more complex. In these there are also slits that direct water to the afferent channels. From there, it is directed to the vibrating chambers, lined with choanocytes; and communicates with the spongiocella, through efferent channels. The pressure of the water causes it to be expelled easily.