herring-bone hydroid
... that the herring-bone hydroid has two types of feeding polyp which differ in their behaviour?
... that the <b id="mwsQ"><a href="./Halecium_halecinum" id="mwsg" rel="mw:WikiLink" title="Halecium halecinum">herring-bone hydroid</a></b> has two types of feeding <a class="mw-disambig" href="./Polyp" id="mwsw" rel="mw:WikiLink" title="Polyp">polyp</a> which differ in their behaviour?