Waggling around on the inside of our lungs, cilia are tiny hairs that wave harmful bacteria away. Yet similar cilia in the Euprymna scolopes squid hint that there’s more going on. Here a microscope captures part of the squid’s light organ (the ring-shape in blue), while cilia on the outside affect the motion of nearby fluorescently-coloured particles (shown in green and red, overlapping in pink). Fast-moving particles appear blurred (right) compared to slower moving particles in the gentle currents on the left. At home in the sea, squid may use changes in cilia movement to create calm, sheltered zones where 'friendly' or symbiotic, Vibrio fischeri bacteria find an easy path into the organism. The mechanics of these tiny hairs are similar between squid and human, raising a question – do to our own cilia wave certain particles in, as well as flapping unwanted ones away?
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