Smalleye Stingray

Diving with a Smalleye Stingray

Diving with a Smalleye Stingray

The smalleye stingray is a large species of stingray measuring up to 2.2 meters. Rare but widely distributed, around Mozambique, this species may be semi pelagic in nature, inhabiting both deeper waters like Manta Reef only 10km form Guinjata Dive Center in Jangamo province and shallow coastal reefs and estuaries near Barra and Tofo. It is characterized by a diamond-shaped pectoral fin disc much wider than long, a tail that is broad and flattened in front of the spine but whip-like behind, and large white spots over its back.

The very wide shape of the smalleye stingray differs from that of most other members of its family, and may reflect a mode of swimming similar to other rays such as manta rays. This species is aplacental viviparous with litter sizes perhaps as small as one pup.

The smalleye stingray is widely but possibly discontinuously distributed in the Indian and Pacific Oceans, having been reported from off Tofo and Guinjata in Mozambique, Male, India and Malaysia. At Guinjata on Manta Reef smalleye stingrays have been seen swimming over reefs at a depth of 15–25 meters where the water temperature is 23–28 °C. Although it had been presumed to be bottom dwelling, these observations of individuals in mid-water suggest that the smalleye stingray may in fact be semi pelagic in nature.

The smalleye stingray has a distinctive shape among its family: the pectoral fin disc is more than 1.4 times wider than long, with the outer corners forming obtuse angles. The anterior margins of the disc are sinuous and converge on a rounded snout with a slightly projecting tip.

The eyes are small and immediately followed by a pair of much larger spiracles. The mouth is wide and contains five papillae across the floor. The tail is not quite as long as the disc, and is broad and flattened from its base to the stinging spine. After the spine, the tail abruptly becomes thin and cylindrical, with a low, thick fin fold running underneath.

The upper surface of the disc is covered by many large dermal denticles with star shaped bases, concentrated on the snout. This ray is brown to reddish brown above, darkening towards the tip of the tail, and white below, becoming slightly dusky at the fin margins and on the tail.

The dorsal surface bears characteristic large white spots beside the eyes, around the disc center, and in a row on either side about two-thirds of the way to the pectoral fin tips. There is also a row of small white spots on either side of the tail base. One of the largest stingray species, the smalleye stingray can reach a disc width of 2.2 meters and a total length of 3.2 meters.

The disc shape of the smalleye stingray suggests that it may swim in a fashion unlike other stingrays and more akin to other rays with very broad pectoral fin discs Mantas, flapping its pectoral fins up and down rather than undulating the pectoral fin margins.

Off Manta reef most individuals are accompanied by multiple cobia, known parasite of this species is the tapeworm, which infests the spiral valve intestine. As with other stingrays, the smalleye stingray is aplacental viviparous with the developing embryos being sustained by york and later uterine milk secreted by the mother. Newborn rays likely measure 31–33 cm across.