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Pacific halibut are longer than most of their relative flatfishes; their width is about a third of their length.  The tapered head of the halibut houses two independent, telescope eyes on the right side of its body.  Its eyes are oriented to the side of its "big-lip" jaws so that its mouth opens laterally when oriented on its side, as it generally is.  The dark, upper side containing the eyes typically has a uniform grey-brown hue, but tends to assume the coloration of the sea floor when found in its natural habitat.  The underside is snow white in color, resembling the sky from below.  Its exceptional ability to avoid being spotted reduces detection by prey and predators.  Small scales, smooth to touch, are imbedded in the skin on both sides of the body.   

Unlike all other vertebrates, the Pacific halibut is not dorso-ventrally orientated, but rather, laterally.  This adaption has evolved within the order Pleuronectiformes to better suit H. stenolepis as a bottom-dweller.  For the purpose of making anatomical references more clear in this paragraph, I will refer to the halibut as if it were being looked at dorso-ventrally, as pictured in black and white above and to the right.  The anal and pelvic fins on the "ventral" side are merged together to form one long fin that extends from below the gill slits to the tail.  The longer dorsal fin on the top of the body stretches from the head to the tail.  Each of the two lengthy fins broaden outwards from the body, coming to a point at the center of the fish, and then taper off again towards the tail.  These elongated, broadened fins help the flatfish to maintain a lateral balance.  The halibut's pectoral wings on the left and right sides of its body serve to orient it in the water, while the V-shaped muscular caudal fin provides most of the thrust.

The picture on the left shows a halibut's head as it is being pulled out of the water.  As you can see, the eyes are oriented to the right side of its mouth due to its unique development.  The photo on the right depicts the colored, right side of the fish as it emerges from the water.  Special thanks to Captain Andrew Mezirow for the images.

Go on to learn more about the behavior of the Pacific halibut.