Round Stingray

The Round Stingray (Urobatis halleri) is a small, common stingray of the family Urotrygonidae, found along the Pacific coast of North America from central California to the Gulf of California and further south. It is notable for its distinctly rounded disc shape, lacking the pointed wingtips of many other stingrays, and for forming dense seasonal aggregations of hundreds to thousands of individuals in warm shallow bays, most famously at Seal Beach, California. These gatherings are linked to mating and possibly to warmer water for pupping. Round Stingrays are a frequent cause of minor stingray injuries to waders and swimmers due to their habit of resting buried in shallow surf-zone sand.

• Disc: small, rounded to oval, without pointed wingtips
• Color: sandy brown, grey-green, or olive above, often mottled to blend with sediment
• Snout: short and rounded, not elongated
• Tail: relatively short and thick compared to whiptail stingrays, with a single venomous spine
• Size: disc width typically 15-23 cm, among the smaller stingray species

Its small size, rounded disc without angular wingtips, and short thick tail distinguish it from larger whiptail stingrays and from ray species with pointed disc corners.

Round Stingrays inhabit shallow, warm coastal waters along the eastern Pacific, ranging from central California to the Gulf of California and south along the coast of Mexico. They favor sandy or muddy substrates in bays, estuaries, and gently sloping surf zones, typically in water less than a few meters deep, and are well known for gathering in especially large numbers in warm, shallow lagoons and bays during summer months. Their preference for shallow sandy flats brings them into frequent close contact with human waders and swimmers.

Round Stingrays spend much of their time resting partially buried in sand, using camouflage to avoid predators while ambushing small invertebrate prey such as worms, shrimp, and small crustaceans. They form some of the densest known stingray aggregations, particularly at warm, shallow sites where hundreds to thousands of individuals gather, likely for mating and thermal benefits related to reproduction. Reproduction is ovoviviparous, with females producing small litters of pups after gestation. Their tail spine, while capable of delivering a painful defensive sting, is used solely for protection against threats such as being trodden on, not for hunting.