Abstract:
Ciliates are unicellular organisms that are ubiquitous in the marine environment and important consumers of phytoplankton and flagellates. The feeding in ciliates is complex and relies in many species on coordinated motion in bands of transversal rows of cilia known as membranelles. We explore the feeding in the ciliate Euplotes vannus that uses a single membranelle band to both generate feeding flow, retain food particles, and transport them to the mouth region. We determine the clearance rate using particle tracking and estimate the flow-generating force by fitting a point force model to the observed flow. To obtain a mechanistic understanding of the feeding, we use high-speed video-microscopy. The cilia move parallel to the membranelle band towards the mouth region in the power strokes, and a metachronal wave propagates away from the mouth region parallel to the band and outwards along the membranelles. From the inside of the band, a gap therefore opens between neighbouring membranelles, and while food particles are retained, water is drawn in and pushed across the membranelle band as the gap closes from the inside. We rationalize our findings in a model that compares favourably with our observations of clearance rate and membranelle motion.
This is joint work with Mads Rode and Thomas Kiørboe.
Bio:
Anders Andersen received his MSc in physics and chemistry in 1999 from the University of Copenhagen and his PhD in physics from the Technical University of Denmark in 2002. He did postdoctoral research from 2002 to 2005 at the Department of Theoretical and Applied Mechanics at Cornell University. He was employed as Assistant Professor at the Department of Physics at the Technical University of Denmark from 2006 to 2010 and as Associate Professor from 2010 to 2020. Since 2020 he has worked as an Associate Professor at the Centre for Ocean Life, National Institute of Aquatic Resources, Technical University of Denmark. Anders Andersen’s research focuses on fluid flows in physical and biological systems, and he currently works experimentally and theoretically on the fluid dynamics of swimming, feeding, and predator avoidance of small aquatic organisms.