Pollicipes polymerus
... that the gooseneck barnacle Pollicipes polymerus will become sterile if there are no others within 20 cm (8 in)?
... that the <a class="mw-redirect" href="./Gooseneck_barnacle" id="mwCMw" rel="mw:WikiLink" title="Gooseneck barnacle">gooseneck barnacle</a> <i id="mwCM0"><b id="mwCM4"><a href="./Pollicipes_polymerus" id="mwCM8" rel="mw:WikiLink" title="Pollicipes polymerus">Pollicipes polymerus</a></b></i> <i id="mwCNA">(several pictured)</i> will become <a href="./Sterility_(physiology)" id="mwCNE" rel="mw:WikiLink" title="Sterility (physiology)">sterile</a> if there are no others within <span about="#mwt36" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"20"},"2":{"wt":"cm"},"3":{"wt":"0"},"abbr":{"wt":"on"}},"i":0}}]}' id="mwCNI" typeof="mw:Transclusion">20</span><span about="#mwt36" typeof="mw:Entity"> </span><span about="#mwt36">cm (8</span><span about="#mwt36" typeof="mw:Entity"> </span><span about="#mwt36">in)</span>?