Q.Name the system responsible for feeding, respiration and waste removal that is characteristic of phylum Porifera.

The phylum of sponges, the simplest multicellular animals, standing at the cellular level of organisation, mostly marine, sessile and asymmetrical. Its defining feature is the water-transport (canal) system: water enters through numerous ostia into a central spongocoel and exits through the osculum, driven by flagellated collar cells called choanocytes that also trap food for intracellular digestion (sponges have no gut). The body is supported by an internal skeleton of calcareous/siliceous spicules and/or protein spongin fibres. Sponges are typically hermaphrodite, reproduce asexually by budding/fragmentation and sexually with internal fertilisation, and undergo indirect development through a free-swimming larval stage. Examples: Sycon, Spongilla, Euspongia.