Cilia-driven fluid vortices deliver symbiotic bacteria onto the mucociliary olfactory organ of the bobtail squid

Motile cilia at the olfactory organ of bobtail squid Euprymna generate vortical flow that captures symbiont-sized particles and Vibrio fischeri more strongly than inert beads.

• Why it matters: Early colonization occurs when symbionts are scarce (<10 cells per millilitre), yet the host senses them before direct biochemical signaling from the light organ is possible.
• What they did: The study characterized cilia-driven flow and bacterial/bead capture at the olfactory organ in hatchlings of Euprymna scolopes and Euprymna berryi, plus three non-symbiotic cuttlefish and squid species, tracking accumulation over time.
• The result: In Euprymna, beads accumulate more strongly at the olfactory organ than at the light organ over the same exposure time, and swimming Vibrio fischeri are retained an order of magnitude more strongly; vortical flow persists to at least 96 h post hatching.