The Porifera (To bear pores)

Major Characteristics Animal Characteristics Asymmetrical or Radial Symmetry Cell Specialization without Distinct Tissue or Organ Systems Non-Mobile adult stage that has a central cavity through which water circulates

Body and Cell Types The sponge brings in water through numerous pores and excretes through a large pore called the osculum Pinocytes Amoeboid Mesenchyme Cells Choanocytes

Feeding As water is drawn in by the flagellated choanocytes nutrient particles get trapped in a ring of microvilli around the flagella The particles are transferred to the base of the collar where they are take into the cell and digested inside food vacuoles Nutrients are passed around the sponge by the amoeboid cells

Reproduction Most are monoecious but sperm and egg production usually don’t coincide Some choanocytes go through meiosis to form sperm or eggs Sperm are released through the osculum and are trapped by other sponges as in food. In the mesohyl, the sperm and egg unit forming the zygote As the zygote develops it becomes a flagellated larva and leaves the parent sponge Finally, it settles on the ground where it develops into an adult sponge