Spiny Stingray, Urotrygon munda: The Spiny Stringray has an overall light coloration and a white underside. They have discs that are rounded and approximately equal and length and width. The head has a weakly pointed short snout with small eyes; the front margin of the disk is straight to slightly convex.
The tail fin is short and an elongated oval with one large spine inserted before the middle of the tail. The disc is covered with relatively large, strong, recurved denticles with star-like bases densely covering the entire disk and tail. There are one or two scattered rows of recurved spines that run from along the mid-back to the tail spine.
They reach a maximum size of 16 inches and are found up to 150 feet deep in the water column in shallow, coastal waters over soft bottoms. They stir the bottom with their pectoral fins in order to dislodge small crustaceans, small fish, mussels, and worms, on which they feed.
The Spiny Stingray can be easily confused with the Blotched Roundray, Urotrygon chilensis (large blotches on the back, limited denticles); the Panamic Roundray, Urotrygon aspidura (lacks denticles); and Roger’s Roundray, Urotrygon rogersi (concave front disc margin).
In Mexican waters the Spiny Stingray is found from just north of Magdalena Bay to Cabo San Lucas along the Pacific side of Baja, throughout the Sea of Cortez, and along the coast of the mainland south to Guatemala. They are of limited interest to most due their size and rarity.
The Spiny Stingray is a member of the Urolophidae Family which includes Round Rays and Stingrays which are known in Mexico as Rayas Redondas.
Globally, there are 10 members of the Urotrygon Genus, of which four are found in Mexican waters. The Round Rays are very similar to the Stingrays, characterized by an oval or near circular disc profile with continuous pectoral fins around the head. They have slender tails that are usually longer than the disk with one large venomous spine located mid-length of an elongated, oval, well-developed tail fin. Most species of this family are bottom-dwellers in shallow, coastal waters. They feed on buried mollusks and crustaceans. Caution: These rays are potentially dangerous as they can inflict wounds with intense pain and slow recovery.