Nielsen Claus
Natural History Museum of Denmark (University of Copenhagen), Zoological Museum, Universitetsparken 15, DK-2990, Copenhagen, Denmark.
Biol Rev Camb Philos Soc. 2023 Feb;98(1):376-385. doi: 10.1111/brv.12909. Epub 2022 Oct 10.
Choanoflagellates and sponges feed by filtering microscopic particles from water currents created by the flagella of microvillar collar complexes situated on the cell bodies of the solitary or colonial choanoflagellates and on the choanocytes in sponges. The filtering mechanism has been known for more than a century, but only recently has the filtering process been studied in detail and also modelled, so that a detailed picture of the water currents has been obtained. In the solitary and most of the colonial choanoflagellates, the water flows freely around the cells, but in some forms, the cells are arranged in an open meshwork through which the water can be pumped. In the sponges, the choanocytes are located in choanocyte chambers (or choanocyte areas) with separate incurrent and excurrent canals/pores located in a larger body, which enables a fixed pattern of water currents through the collar complexes. Previous theories for the origin of sponges show evolutionary stages with choanocyte chambers without any opening or with only one opening, which makes separation of incurrent and excurrent impossible, and such stages must have been unable to feed. Therefore a new theory is proposed, which shows a continuous evolutionary lineage in which all stages are able to feed by means of the collar complexes.
领鞭毛虫和海绵通过过滤水流中的微小颗粒来进食，这些水流是由位于单个或群体领鞭毛虫细胞体上的微绒毛领复合体的鞭毛以及海绵中的领细胞产生的。这种过滤机制已为人所知超过一个世纪，但直到最近才对过滤过程进行了详细研究并建立了模型，从而获得了水流的详细图像。在单个和大多数群体领鞭毛虫中，水在细胞周围自由流动，但在某些形态中，细胞排列成开放的网络，水可以通过该网络被泵送。在海绵中，领细胞位于领细胞室（或领细胞区），在较大的身体中有独立的进水和出水管道/孔隙，这使得通过领复合体的水流具有固定模式。先前关于海绵起源的理论显示了领细胞室没有任何开口或只有一个开口的进化阶段，这使得进水和出水无法分离，这样的阶段必定无法进食。因此提出了一种新理论，该理论显示了一个连续的进化谱系，其中所有阶段都能够通过领复合体进食。
