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