The fluid dynamics of barnacle feeding

Kristian Maar*, Uri Shavit, Anders Andersen, Thomas Kiørboe

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Sessile barnacles feed by sweeping their basket-like cirral fan through the water, intercepting suspended prey. A primary component of the diet of adult barnacles is copepods that are sensitive to fluid disturbances and capable of escaping. How do barnacles manage to capture copepods despite the fluid disturbances they generate? We examined this question by describing the feeding current architecture of 1 cm sized Balanus crenatus using particle image velocimetry, and by studying the trajectories of captured copepods and the escapes of evading copepods. We find that barnacles produce a feeding current that arrives both from behind and the sides of the barnacle. The flow from the sides represents quiescent corridors of low fluid deformation and uninterrupted by the beating cirral fan. Potential prey arriving from behind are likely to encounter the cirral fan and, hence, capture here is highly unlikely. Accordingly, most captured copepods arrived through the quiet corridors, while most copepods arriving from behind managed to escape. Thus, it is the unique feeding flow architecture that allows feeding on evasive prey. We used the Landau-Squire jet as a simple model of the feeding current. For the Reynolds number of our experiments, the model reproduces the main features of the feeding current, including the lateral feeding corridors. Furthermore, the model suggests that smaller barnacle specimens, operating at lower Reynolds numbers, will produce a fore-and-aft symmetric feeding current without the lateral corridors. This suggests an ontogenetic diet shift from non-evasive prey to inclusion of evasive prey as the barnacle grows.
Original languageEnglish
Article numberjeb246541
JournalJournal of Experimental Biology
Issue number5
Publication statusPublished - 2024


  • Suspension-feeding
  • Hydro-mechanical sensing
  • Copepods
  • Particle image veolcimetry (PIV)
  • Landau-squire jet


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