Porifera
Porifera, or pore bearers, are also known as sponges. They mostly live under water, or in moist climates. They have many cells that run throughout their body that help to protect their exoskeleton. Sponges don't have a mouth, so food is diffused through their body. These cells absorb all the food into the stomach, basically they are filter feeders.
Bath sponge
A Bath Sponge, or a metazoan, is a Filter feeder. It does not have a mouth, neither does it have an anus. Everything it takes in and execrates is done by transmission through the pores. Feeding is done by diffusion, osmosis, pinoytosis or phagocytosis. Its body is full of absorbing ostia pores and has canals and passageways to distribute the energy it absorbed. If a food particle is to large to be absorbed, it is execrated through the osculum.
grantia
Grantia or Scypha is a calcareous marine sponge. In this sponge's digestive system, the internal and external canals transport oxygen and food throughout the body. These canals also are used for execration. food enters through the ostia and goes through internal prosopyles pores. Choanocytes control the water flow, which is where the food is. The food is then suspended to the flagella and digested through phagocytosis and amebocytosis, which controls absorbing of energy.
basket sponge
The Basket Sponge or Demosponge also relies on the movement of water flowing throughout their body to obtain the nutrients they need. Outside water goes throughout the ostia pores and into the filter chamber (Atrium), where then food is either digested through Phagocytosis or execrated through the osculum.