Yellow Stingray
The yellow stingray, Urobatis jamaicensis, is a species of stingray in the family Urolophidae. It is found in shallow, near-shore environments in the tropical western Atlantic Ocean, including the Gulf of Mexico and the Caribbean Sea. This ray is normally harmless to humans, but its venomous tail spine can inflict a painful wound if it is accidentally stepped on. Though not targeted by fisheries, it is taken as bycatch and may also be threatened by habitat loss.
Yellow stingrays are found in coastal tropical waters in the western Atlantic Ocean, from Cape Lookout, North Carolina, around Florida, and throughout the Gulf of Mexico and the Caribbean Sea (including the Greater and Lesser Antilles), south to Central America and the northern coast of South America. It is common around the Florida Keys and parts of the Antilles but not thought to be abundant elsewhere. This species usually occurs in shallow habitats, such as bays, estuaries, and low-energy surf zones, from the shoreline to a depth of 25 m. It favors hard, live-bottom insular habitats, as well as sandy, muddy, and grassy environments, and in and around coral reefs. In Mexico, it is reported from a salinity range of 26-40 ppt.
This small species grows to a maximum of 66 cm long and 35 cm across. Like other members of the family, it is characterized by a round pectoral fin disc. The rear margin of the pelvic fins are rounded, and the dorsal fins are absent. The tail is shorter than the disc and has a well-developed caudal fin that extends around the tip. A venomous, doubly serrated tail spine is located just forward of the caudal fin. The teeth number approximately 30 in both jaws and are sexually dimorphic; females and juveniles have closely arranged, oval teeth with low cusps, while males have upper teeth that are more loosely spaced and slightly blunt with high conical cusps. This trait may enable the males to better grip the females during copulation. There are several papillae on the floor of the mouth.
The color and pattern of yellow stingrays is highly variable, though most individuals follow one of two schemes: a dark greenish or brown reticulated pattern on a pale background, or a close-set pattern of minute white, yellow, or golden spots on a dark green or brown background. The underside is yellowish or brownish-white. It is capable of changing color to match its environment. Newborns lack dermal denticles, but shortly after birth low blunt tubercles start to develop on the mid-dorsal region and recurved thorns develop along both sides of the dorsal margin of the caudal fin. In larger individuals, the dorsal tubercles extend forward to the back of the orbit and between them, and a lateral band of thorns develops over each shoulder.
Yellow stingrays are often found buried in the substrate. They feed on shrimps, and possibly also small fishes, clams, and worms. It has been suggested that they raise the front part of their discs to create a shaded area that attracts prey seeking shelter. They may also excavate pits to uncover prey in a manner similar to the related round stingray. Yellow stingrays are preyed upon by large carnivorous fish such as tiger sharks (Galeocerdo cuvier), and are parasitized by cestodes such as Acanthobothrium cartagenensis, Phyllobothrium kingae, Rhinebothrium magniphallum, and Discobothrium caribbensis.
The mating behavior of the yellow stingray has been observed in February near Tobacco Caye on the Belize Barrier Reef. In water 2.5 m deep, the mating pair swam together with the male slightly above and behind the female, attempting to bite the rear margin of her pectoral disc. Once the male successfully bit and held on to the female, he swung beneath her so they were aligned abdomen-to-abdomen and inserted one of his claspers into her cloaca. Copulation lasted for four minutes. These and other observations suggest that the yellow stingray has a reproductive peak around February and March, though it is unknown whether they have a well-defined annual or biennual breeding cycle like the related round stingray. Like other stingrays, the yellow stingray is ovoviviparous, bearing litters of 3-4 pups; the gestation period is unknown. The embryos have discs that are wider relative to their length than adults, and have a fleshy lobe that covers most of the spiracle opening. Males reach maturity at 15-16 cm across.
The yellow stingray is usually docile and easily approached by divers; accidental injuries from its tail spine are painful, but rarely life-threatening. It is not targeted by commercial fisheries but is taken as by-catch and collected for the aquarium trade; the impact of these activities on its population is unknown. The IUCN Red List currently assesses the species as of Least Concern, but it may be vulnerable to degradation of its breeding habitats.
Photograph by Courtney Sage
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