In the water, a flagellate powers a current by beating its flagella and draws food closer to capture and engulf it.

PhD defence about feeding mechanisms at the marine microscale

Thursday 14 Sep 23


Sei Suzuki-Tellier
PhD Student
DTU Aqua


Thomas Kiørboe
DTU Aqua


This PhD project was funded by the Independent Research Fund Denmark and the Villum Foundation via Centre for Ocean Life, a VKR Centre for Excellence.

On 26 September 2023, Sei Suzuki-Tellier will defend her PhD thesis. It is possible to attend the defence at DTU Lyngby Campus or online.

Phagotrophic nanoflagellates are single-cell organisms (2 – 20 μm) with one or more whip-like extensions, known as flagella, used for feeding and swimming. They are the main consumers of bacteria and picophytoplankton and are important to the energy flow in marine microbial food webs, thereby significantly impacting global biogeochemical cycles.

Despite their ecological significance, their role in aquatic ecosystems, including their feeding mechanisms, remain poorly understood.

In her PhD thesis, Sei Suzuki-Tellier from DTU Aqua investigates the different predation behaviors of phagotrophic nanoflagellates. At this microscale, physical laws become counterintuitive because viscous forces dominate the fluid – like swimming in molasses – impeding predators from contacting their prey. Therefore, the organisms carry out feeding strategies that overcome the physical constraints.

Sei Suzuki-Tellier has used high-speed video microscopy to directly observe the species-specific predation modes of phagotrophic nanoflagellates. The observations have aided theoretical models and computational fluid dynamic simulations to mechanistically study the various feeding processes. She highlights two specialized adaptations that enhance capture efficiency: the ‘hairy’ flagellum and the ventral groove with a ‘vaned’ flagellum. In addition, she documents, for the first time, the activity of the ‘wave’ in this ventral groove and the prey size range of these specific nanoflagellates.

About the PhD defence

Sei Suzuki-Tellier will defend her PhD thesis "Feeding mechanisms in phagotrophic nanoflagellates. Predation in the Low Reynolds Number World” on Tuesday 26 September 2023, 13:00 on Zoom and at DTU, building 358, room 060B, 2800 Kgs. Lyngby. 


  • Principal supervisor: Professor Thomas Kiørboe, DTU Aqua
  • Co-supervisor: Associate Professor Anders Andersen, DTU Aqua


  • Professor Andre Visser, DTU Aqua (chair)
  • Senior Lecturer Kirsty Wan, University of Exeter, UK
  • Research Scientist Ramon Massana, Institut de Ciències del Mar, Spain

Chairperson at defence

  • Senior Researcher Jane Behrens, DTU Aqua
Learn more

A copy of the thesis is available by e-mail on request. Please contact Sei Suzuki-Tellier,

How to attend the defence


Everybody is welcome to attend Sei Suzuki-Tellier’s defence at DTU, building 358, room 060B, 2800 Kgs. Lyngby. 



The defence can also be followed online on Zoom using this link:
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. 



Tuesday, 26 September 2023, 13:00-16:00