Hydrodynamics in early animal evolution

Claus Nielsen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

7 Citations (Scopus)
18 Downloads (Pure)

Abstract

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.

Original languageEnglish
JournalBiological Reviews
Volume98
Issue number1
Pages (from-to)376-385
Number of pages10
ISSN1464-7931
DOIs
Publication statusPublished - 2023

Bibliographical note

Publisher Copyright:
© 2022 Cambridge Philosophical Society.

Keywords

  • Choanoflagellata
  • Eumetazoa
  • evolution
  • filter feeding
  • Porifera
  • water currents

Cite this