California Butterfly Ray, Gymnura marmoratai: The California Butterfly Ray is brown in color, at times covered with small brown or black spots. The width of the disc is 1.5 times the length, reaching a maximum size of 5 feet wide and 3 feet long. The front margin of the disc is slightly concave and the rear margin rounded. The snout is blunt except for a protruding tip.
The short tail is approximately one-half the length of the disc and there is no caudal fin. A key to identification is thatthe distance between the eyes is greater than the distance from the eyes to the tip of the snout; the eyes are located at approximately 16 percent of the body length.
This fish species is easily confused with the Long Snout Butterfly Ray, Gymnura crebripunctata (straight disc margins, tip of snout further than distance between eyes located at approximately 22 percent of the body length).
The California Butterfly Ray is found in shallow inlets, bays, and lagoons over sandy bottoms at depths between 90 and 300 feet. It has a broad distribution and is found in all Mexican fishing waters. However, it appears to be absent from around the oceanic islands. The California Butterfly Ray is viewed as marginal table fare.
It is a member of the Gymnuridae Family and Gymnura Genus. Globally there are a total of 16 species of the Gymnura Genus, of which only 2 are found in the Eastern Tropical Pacific. The Butterfly Rays have a rhomboidal disc that is much wider than it is long, pectoral fins which are not separated from the head giving rise to a triangularly shaped body, a bluntly pointed snout, a very short tail with 1 or 2 large serrated spines, no tail fin, and no dorsal fin. Most species of this family are bottom dwellers, found in shallow coastal waters. They feed on buried bivalves, crabs, mollusks, and crustaceans.