Feeding

Sponges obtain nourishment by the filter feeding mode of life. They feed by 'filtering' tiny particles (sometimes bacteria) out of the water which is pumped through their body by their collar cells. Throughout a day, a huge amount of water is processed. For example, a 10 cm Leucandra, a type of sponge, pumps up to 22.5 litres per day. The sponge's body shape is made so that the water passes directly over the cells which are responsible for the gathering of food and gas exchange. As the small particles of food are being captured, waste and reproductive products are being removed. The collar cells digest the food and pass them into the body by specialized cells.

Because of the toxins and chemicals sponges are able to produce, they are protected by many preditors. Nudibranchs are a remarkable type of animal which has become immune towards the sponges toxins and are also able to use the chemicals in their own defense.
Many virus's and bacteria have the power to cause disease to sponges and in the 1930's a disease caused by fungi attacked commerical bath sponges and almost killed them all.