National Geographic : 1921 Jan
58 THE NATIONAL GEOGRAPHIC MAGAZINE Undersea Photograph by Dr. W . H. Longley UNDERSEA STUDY OF A FAMILY GROUP OF YELLOW GRUNTS To realize the full value of this amazing photograph, one must remember that these multihued fish are at home among the coral and sea-fans of their natural habitat, many feet beneath the surface of the Gulf Stream. The yellow grunt is one of the species of fishes which makes a croaking or grunting sound, a fact from which it derives its name. A distinguishing feature of this fish is its bright red or orange color at the base of the jaws and inside the mouth. The color patch is revealed to its fullest extent when the mouth is opened wide in the presence of an enemy, or when it invites the services of the butterfly fish to enter between its jaws and extract certain parasites attached to the walls of its mouth (see Color Plate VII).