The shape of a fish's body - the external appearance resulting from adaptation to a particular way of life, method and speed of swimming. It depends on the shape and position of the fins, the presence or absence of various growths, spines, barbs and other formations on the head, body, shape and position of the mouth. There are several types: torpedo-shaped (tunas, salmonids, herring), arrow-shaped with an elongated body and unpaired fins drawn back (shuka, garfish), flattened at the sides (flounder, bream); serpentine (eel, sea needlefish). Marine fishes are characterised by dentiform (herring king), globular (pinagore, cusk), flat (stingray, sea devil) body forms. There are many transitional forms, for example the pufferfish is an intermediate between serpentine and ribbon-shaped.