Siconids

Siconids are a group of organisms within the phylum Porifera, commonly known as sponges. They belong to the class Calcarea, which is characterized by spicules composed of calcium carbonate. The defining feature of siconids is their complex canal system, which is intermediate between the simpler asconoid and the more elaborate leuconoid structures found in other sponges.

In the siconoid organization, the body wall is folded both externally and internally, creating radial canals lined with choanocytes, the flagellated cells responsible for feeding and water circulation. Water enters the sponge through small pores called ostia on the outer surface, flows into these radial canals, and then passes into a central cavity, the paragaster, before exiting through a larger opening called the osculum. This arrangement allows for a larger surface area for choanocytes compared to asconoid sponges, while being less complex and less efficient in water pumping than leuconoid sponges. Siconids are typically sessile, attaching themselves to substrates in marine environments. Their reproduction can be both sexual and asexual. They play a role in marine ecosystems by filtering water and providing habitat for smaller organisms.