A ciliate generating a feeding current visualized by color-coded particle trajectories. Illustration: Mads Rode

PhD defence about the physics of microbial feeding

Tuesday 01 Feb 22


Mads Rode
Research Assistant
DTU Aqua


Anders Peter Andersen
Associate Professor
DTU Aqua
+45 35 88 34 11

On 25 February 2022, Mads Rode from DTU Aqua will defend his PhD thesis. It is possible to attend the defence at DTU or online.

Small planktonic organisms, which are not visible to the naked eye, play an essential role in marine ecosystems. Many of these organisms feed by filtering large amounts of water containing prey in low concentrations. In his PhD project, Mads Rode has—by combining physics and biology—investigated how microorganisms manage to clear sufficiently large volumes of water to sustain a living.

Mads Rode and his colleagues have quantified how the feeding current is affected by the presence of the nearby surfaces to which the organisms attach. In addition, they have investigated the mechanism behind the ciliate Euplotes vannus' way of feeding by means of a membranelle band. Ciliates are common single-celled aquatic organisms. 

Through microscope observations and high-speed video recordings, Mads Rode has documented how the water flows through the membranelle band while the food particles are retained on one side of the band. The studies have also revealed how the band by its motions explains the filtration of a flow equivalent to the clearance rate as well as the overall structure of the prey size spectrum.

It is difficult to collect good observations of microorganisms moving around when foraging. Mads Rode demonstrates in his PhD project that it is possible to tether the microorganisms with ultrasound. This is a useful alternative to either waiting for the microorganisms to come into the focal plan of the microscope or to tether them in an intrusive way. 

About the PhD defence

Mads Rode will defend his PhD thesis "Physics of microbial feeding. Studies of feeding flows near surfaces, ciliate filtration, and non-intrusive tethering of microswimmers" on Friday 25 February 2022, 1:00 p.m. (CET) at DTU, Asmussens Allé, 2800 Kgs. Lyngby, building 303A, auditorium 43 and on Zoom (please find link below). 


  • Principal Supervisor: Associate Professor Anders Peter Andersen
  • Co-supervisor: Professor Thomas Kiørboe


  • Professor Andre Visser, DTU Aqua (chair)
  • Professor Stuart Humphries, School of Life Sciences, University of Lincoln, UK 
  • Dr. Kirsty Y. Wan, Living Systems Institute, University of Exeter, UK

Chair at defence

  • Professor Torkel Gissel Nielsen, DTU Aqua
Learn more

A popular science summary of the thesis can be downloaded here 

A copy of the thesis is available by e-mail on request. Please contact Karin Stubgaard, stub@aqua.dtu.dk

Link to Zoom and guidelines for online attendance

It is possible to attend Mads Rode’s defence on Zoom using this link: https://dtudk.zoom.us/j/61467674041

Please, enter the meeting 10 minutes prior to the defence proceedings are scheduled to start. All participants are muted per default, but we ask you to double check that your microphone is turned off at all times. There will be instructions regarding the proceedings in the beginning of the defence.

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