The barreleye fish is a deep sea fish that is usually under 20 cm long (although some species can be larger). They live in the deep ocean depths where the sunlight can't reach. This type of environment often causes some unique adaptations. the barreleye fish has tubular eyes that protrude from their skull but are enclosed in their transparent dome. These type of eyes are very good at collecting any little bit of light that may be finding its way to the deep ocean depths. The eyes of the barreleye fish generally look up so they are able to detect slight movements in their prey directly above them. For awhile, scientists believed that the eyes could only look up but recent studies have indicated that the barreleye fish is able to direct their unique eyes forward to see what they are eating. These astonishing adaptations just go to show how incredible evolution can be and that there are no limits to an animals survival in this harsh world.