Choanocyte
Choanocytes (also known as "collar cells") are cells that line the interior of asconoid, syconoid and leuconoid body types of sponges that contain a central flagellum, or cilium, surrounded by a collar of microvilli which are connected by a thin membrane.
They make up the choanoderm, a type of cell layer found in sponges.
By cooperatively moving their flagella, choanocytes filter particles out of the water and into the spongocoel, and out through the osculum.
This improves both respiratory and digestive functions for the sponge, pulling in oxygen and nutrients and allowing a rapid expulsion of carbon dioxide and other waste products.
Molecular phylogenies indicate that choanoflagellates and metazoans are sister groups.
Representation of a choanocyte
- Flagellum
- Collar
- Flagellar vane
- Glycocalyx layer
- Contractile vacuole , regulates the quantity of water inside a cell
- Golgi apparatus ; modifies proteins and sends them out of the cell
- Mitochondrion , creates ATP (energy) for the cell
- Endoplasmic reticulum , the transport network for molecules going to specific parts of the cell
- Intercellular junction
- Flagellar basal body , ( centriole )
- Nucleus
- Nucleolus
- Electron dense vesicles
- Digestive vesicle (with prey)
- Phagocytic vesicle (with prey)
- Lysosome , holds enzymes