visual system
... that the deep water barreleye fish is so named because of its unusual visual system which uses barrel-shaped, telescopic eyes that are generally directed upwards?
... that the deep water <a href="./Barreleye" id="mwCXo" rel="mw:WikiLink" title="Barreleye">barreleye</a> fish <i id="mwCXs">(pictured)</i> is so named because of its unusual <b id="mwCXw"><a class="mw-redirect" href="./Vision_in_fishes" id="mwCX0" rel="mw:WikiLink" title="Vision in fishes">visual system</a></b> which uses barrel-shaped, telescopic eyes that are generally directed upwards?