Q What are the major cells of which poriferans are made?
Sponges have their external wall covered by flat cells called pinacocytes and having pores well-delimited by special cells called porocytes. The internal wall is filled with choanocytes, flagellate cells specialized in phagocytosis of food brought to the central cavity the choanocyte flagella also sustain the water flux inside the sponge.
Between the inner and the outer coverage of the poriferan body there are cells with amoeboid movement by pseudopods, the amoebocytes since they are embedded in connective matrix, distribute nutrients and amoebocytes move to other cells and they also produce spicules that like a primitive skeleton fill the tissue and support the body structure. Some poriferans have an interior skeleton, an endoskeleton, made of organic and spicules fibers.